REVIEW 3 major objections 4 minor 16 references
The paper claims that adaptive merging of publicly recycled LoRA adapters gives little benefit over simply training a new LoRA on the target task, and that when the target-task LoRA is included in the merge, the choice of other LoRAs barely
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · deepseek-v4-flash
2026-08-02 23:51 UTC pith:P5PGKPLV
load-bearing objection First in-the-wild LoRA-recycling study with a strong target-LoRA baseline; the random-init result is intriguing but hinges on underspecified LoRA rescaling. the 3 major comments →
The Appeal and Reality of Recycling LoRAs with Adaptive Merging
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The discovery is an empirical negative result about adaptive merging from realistic, heterogeneous LoRA pools. Using a unified design space covering LoRA selection, coefficient granularity, activation, and tuning, the authors find that evaluation-based selection and module-level coefficients help when the target-task LoRA is absent, but the advantage nearly disappears when it is present. With the target-task LoRA in the pool, random selection performs as well as informed selection, and randomly initialized LoRAs perform as well as real crowdsourced ones across k=5 to k=30 merged modules. The learned merging coefficients concentrate heavily on the target-task LoRA, while the recycled LoRAs ac
What carries the argument
The central mechanism is a unified design space for adaptive merging that isolates four choices: how LoRAs are selected from the pool (random, evaluation-ranked, parameter-similarity), the granularity of merging coefficients (model, layer, sublayer, module), the coefficient activation (softmax, leaky ReLU, linear), and the tuning procedure (gradient-based or gradient-free). The method the paper calls Ours combines module-level coefficients, evaluation-based selection, and leaky ReLU. The experimental probe that carries the argument is the random-initialization baseline: it replaces real recycled LoRAs with samples from a normal distribution of matched standard deviation while keeping the tar
Load-bearing premise
The claim that randomly initialized LoRAs match curated ones rests on the assumption that rescaling 958 heterogeneous LoRAs (with varying ranks and different target-module configurations) into a common form preserves enough of each LoRA's learned behavior; the paper says the LoRAs were 'rescaled' but does not specify how ranks are padded or sliced or how missing target modules are handled, so the equivalence could be an artifact of comparing already-degraded modules.
What would settle it
Take a heterogeneous pool but align all LoRAs in a rank-preserving way that exactly matches target modules (for example, full SVD expansion instead of padding or slicing), then rerun the random-vs-real comparison with the target-task LoRA included. If real LoRAs now outperform randomly initialized ones, the regularization-only conclusion is refuted. A cheaper check: compare the merged models produced from real and random LoRAs in parameter space — if they are nearly identical after coefficient tuning, the content is genuinely irrelevant; if they differ substantially yet perform the same, the m
If this is right
- Practitioners should benchmark any adaptive-merging method against a target-task LoRA trained on the same few-shot data; on realistic pools, that simple baseline will often erase the apparent gain.
- Including the target-task LoRA in the merging pool is almost necessary for adaptive merging to be competitive; without it, gains over the base model are modest and vary widely across methods.
- Once the target-task LoRA is present, the choice of selection strategy (random, evaluation-based, or similarity-based) has little effect, so compute spent scoring and selecting recycled LoRAs may be wasted.
- Previously reported successes of adaptive merging likely depend on close task relatedness that is easy to arrange in controlled experiments but rare in user-contributed pools; positive transfer decays quickly as relevant LoRAs are removed.
- The recycled LoRAs' specific content may be replaceable by noise, implying a regularization-based explanation; future work should test this directly before assuming knowledge transfer.
Where Pith is reading between the lines
- Editorial inference: If the regularization effect is real, adaptive merging with randomly initialized modules could serve as a cheap, parameter-level noise regularizer for few-shot fine-tuning; this could be tested by comparing it against explicit weight-noise injection during standard LoRA training.
- Editorial inference: The negative result is conditional on how heterogeneous LoRAs are aligned — the paper rescaled modules of varying rank and target-module coverage without specifying the alignment procedure in the main text, so the random-init equivalence may partly reflect information lost during rescaling; a rank-preserving alignment could restore an advantage for real LoRAs.
- Editorial inference: The 62-task, 100-sample evaluation is one operating point; with larger target datasets or different base models, the balance between training a fresh LoRA and merging recycled ones could shift, so the conclusions may not transfer to higher-data regimes.
- Editorial inference: The rapid decay of positive transfer with task dissimilarity reframes the problem as retrieval: the value of a large pool depends on finding rare, highly relevant adapters, and future work should focus on scalable search and ranking rather than on better merging coefficients.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies 'recycling' of nearly 1,000 user-contributed LoRAs from the Hugging Face Hub for Llama 3.1 8B-Instruct. It introduces a unified framework for adaptive merging methods (selection, granularity, activation, tuning), proposes a configuration called 'Ours', and evaluates it against LoraHub, AdaMerging, π-Tuning, and non-adaptive baselines on 62 downstream tasks. The main findings are: (1) adaptive merging improves over the base model but provides little consistent benefit over training a target-task LoRA on the same data; (2) once the target-task LoRA is included in the merging pool, the identity of the other recycled LoRAs matters little, and randomly initialized LoRAs perform comparably to real recycled LoRAs; (3) positive transfer reappears in a bespoke 'in-house' pool of target-task LoRAs, but degrades rapidly when the most relevant LoRAs are excluded. The paper releases code and checkpoints.
Significance. If the negative result holds, this is an important correction to the adaptive-merging literature: it suggests that reported gains from recycling LoRAs may often come from a regularization/optimization effect rather than from positive cross-task transfer, and that the practical value of in-the-wild LoRA recycling is currently limited. The paper's choice to compare against a target-task LoRA baseline and to test a random-initialization control is methodologically valuable. The design-space framework and the release of code/checkpoints are concrete assets. The in-house positive-transfer experiment usefully delineates when the negative result does and does not apply. However, the central claim depends on details of LoRA rescaling/alignment and on the statistical reliability of small performance gaps that are currently not fully reported.
major comments (3)
- [§4.1, §B.1, §D] The alignment/rescaling of heterogeneous LoRAs is underspecified. The main text only says the LoRAs are 'rescaled' (Fig. 1 caption; B.1), and Appendix D gives alignment details only for LoraHub (pad to max rank), TIES (convert to full B@A), and TSV (full B@A). The adaptive methods used for the central random-init experiment (Ours and AdaMerging) require a common rank/module structure, but the paper does not state how ranks are padded, truncated, or projected, nor how LoRAs with missing modules (e.g., the 91 LoRAs targeting only Attn(Q,V)) are treated. This is load-bearing: if alignment distorts real LoRAs, the finding that random reinitialization performs similarly may show only that the rescaled pool contributes little, not that original recycled LoRAs cannot transfer. Please specify the exact alignment procedure for Ours/AdaMerging and verify that alignment preserves a meaningful porti
- [Table 2, Fig. 3] The central equivalence claim is supported by small average differences: with target-task LoRA, at k=30, random selection gives 0.675 and random reinitialization gives 0.672, and Table 2 shows differences on the order of 0.005. No error bars, confidence intervals, or repeated-seed results are reported for Ours, AdaMerging, or LoraHub in these comparisons; non-adaptive methods average 3 seeds but adaptive methods appear to be single runs. Given the magnitude of the effects, please add at least 3 repeats of selection and coefficient tuning for the key methods, or report paired per-task confidence intervals for the Ours vs. random-reinit comparison. Without this, the claim that selection/reinit is negligible is not quantitatively supported.
- [§3, §E] The configuration of 'Ours' is selected on a 20-task ablation set (Section E), and those 20 tasks appear to be part of the 62-task testbed used for final evaluation in Table 2 and Fig. 3. This makes the reported 'Ours' performance partly optimized against the evaluation set. Since the random-init experiment in Fig. 3 also uses 'Ours', the circularity affects the central claim. Please state explicitly whether the 20 ablation tasks belong to the 62, and either hold them out from the final evaluation, or use a nested/non-overlapping selection procedure so that the reported numbers are unbiased.
minor comments (4)
- [Fig. 3] The legend terms 'reinit.', 'rand.', 'eval.' are easy to confuse. 'reinit.' means randomly reinitialized parameters, while 'rand.' means randomly selected real LoRAs. Please use more explicit labels, e.g., 'random init' vs. 'random selection', and define them in the caption.
- [Table 2] The column headers 'w/o LoRA' and 'w/ LoRA' should be 'w/o target-task LoRA' and 'w/ target-task LoRA' to avoid ambiguity, since 'LoRA' is also used for the target-task baseline.
- [Fig. 3, §5] The random-initialization control matches the marginal standard deviations of A and B separately, but the merged update is s·B@A. Coefficient tuning can absorb global scale, but the effective distribution of the product may differ. Please state the exact initialization (including whether the LoRA scaling s is applied) and, if available, include a control that matches the Frobenius norm of the merged update.
- [§C.1] For LoraHub, the text says coefficients are selected by lowest loss on the 'full 100 examples', while other methods use an 80/20 split. Please clarify whether the 20 validation examples are used for LoraHub or whether the optimization directly uses all 100 training examples.
Circularity Check
No significant circularity; the central claims are empirical and the random-init control is a genuine external benchmark.
full rationale
The paper's load-bearing claims are empirical: adaptive merging improves over the base model but gives limited benefit over a target-task LoRA; the choice of recycled LoRAs matters little once the target-task LoRA is in the pool; randomly initialized LoRAs perform similarly to real recycled LoRAs; and positive transfer appears only with highly relevant in-house LoRAs. None of these conclusions is derived by definition from a fitted parameter. The random-init experiment is a proper control: it keeps the same merging method and target-task LoRA while replacing the recycled LoRAs' learned content with random values, so it can falsify the positive-transfer explanation. The only mild concern is that the 'Ours' configuration was chosen via ablations on 20 tasks, and the paper does not explicitly state whether those 20 are disjoint from the 62-task evaluation; if they overlap, the reported Ours performance is partly selected on the testbed. However, the manuscript never states the overlap, and the random-versus-evaluation equivalence is shown across design choices in the ablations and replicated in the main experiment, so it is not an artifact of that configuration choice. Self-citations to Je & Raffel, Tam et al., and Li et al. supply benchmark tasks or design approximations, not load-bearing proofs of the empirical findings. Thus I find no step that reduces by construction to its own inputs; the appropriate score is low.
Axiom & Free-Parameter Ledger
free parameters (5)
- Selected LoRA count k =
30 (default; also 5, 10, 20)
- Target-task sample budget =
100 (80 train / 20 val)
- Target-task LoRA rank/steps/LR =
r=64, 400 steps, LR=3e-4
- Coefficient-tuning steps/LR =
100 steps, LR=5e-2
- 'Ours' method configuration (module-level, leaky ReLU, evaluation selection) =
Module granularity, leaky ReLU activation, eval-based selection, gradient-based tuning
axioms (6)
- domain assumption Llama 3.1 8B-Instruct is an adequate base; all pool LoRAs are assumed to target compatible base models (including quantized variants).
- domain assumption The filtered pool of 958 LoRAs is representative of 'in-the-wild' modules.
- domain assumption Heterogeneous LoRAs (varying ranks and target modules) can be rescaled/aligned for merging without losing their functional content.
- domain assumption The 62-task benchmark from Je & Raffel (2025) and Tam et al. (2024b) is a fair testbed for measuring positive transfer.
- domain assumption Gradient-based coefficient tuning with 100 steps reaches a sufficiently good optimum.
- domain assumption Randomly reinitialized LoRAs preserve the same parameter scale as trained LoRAs, so the comparison isolates the effect of learned content.
read the original abstract
The widespread availability of fine-tuned LoRA modules for open pre-trained models has led to an interest in methods that can adaptively merge LoRAs to improve performance. These methods typically include some way of selecting LoRAs from a pool and tune merging coefficients based on a task-specific dataset. While adaptive merging methods have demonstrated improvements in some settings, no past work has attempted to recycle LoRAs found "in the wild" on model repositories like the Hugging Face Hub. To address this gap, we consider recycling from a pool of nearly 1,000 user-contributed LoRAs trained from the Llama 3.1 8B-Instruct language model. Our empirical study includes a range of adaptive and non-adaptive merging methods in addition to a new method designed via a wide search over the methodological design space. We demonstrate that adaptive merging methods can improve performance over the base model but provide limited benefit over training a new LoRA on the same data used to set merging coefficients. We additionally find not only that the specific choice of LoRAs to merge has little importance, but that using LoRAs with randomly initialized parameter values yields similar performance. This raises the possibility that adaptive merging from recycled LoRAs primarily works via some kind of regularization effect, rather than by enabling positive cross-task transfer. To better understand why past work has proven successful, we confirm that positive transfer is indeed possible when there are highly relevant LoRAs in the pool. We release the model checkpoints and code online.
Figures
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discussion (0)
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