Which workflow settings multiply or divide GPU cost per job in ComfyUI: CFG 1, regional sampling, recovery samplers, cached partial re-runs?

Problem. Two workflows with the same steps and resolution can differ by a large factor in model evaluations. Conditions. ComfyUI core samplers.py at 9fe7ef76; Impact Pack Regional Sampler tutorial (default-branch text, no commit id); a Wan 2.2 end-frame example. Levers. (1) CFG 1.0: in the sampler, when cond_scale is close to 1.0 (and disable_cfg1_optimization is not set) the unconditional branch is dropped, so each step evaluates the model once instead of twice (inference: count of passes; see C3-B582-05 for why negatives then do nothing). (2) Regional Sampler: a base-only stage runs base_only_steps, then each step does base-region sampling plus one sampling per region, and the tutorial states that the optional additional_mode recovery 'requires a longer time for sampling because a second sampling is performed at each step in each region'. A rough model (inference): passes per step = 1 + R (+ R with recovery) for R regions, so budget about (1+R) to (1+2R) times a single-sampler step. (3) Caching: re-running with only a downstream field changed re-executes only downstream nodes; the end-frame example says changing the extracted frame index reruns 'the frame extraction part only', which needs a fixed seed (see C3-B574-01 and C3-B579-04). Method. Estimate cost per job as cold cost x (fraction of nodes whose inputs changed) x passes-per-step multiplier, then add retries (C3-B584-09 and C3-B574-18 for duplicate-charge risk). Failure modes. A random seed or a changed upstream widget invalidates the cache silently; regional sampling with a mismatched composition gives blurry output the tutorial warns about, which raises retry rate. Limitations. Multipliers are inference from descriptions; no timings measured. Version and date. ComfyUI 9fe7ef76. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Pass-count multipliers are my model; timings not measured. Tutorial text is not pinned to a commit. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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