Good paper for selecting your skill files.
Before distilling a skill bank, log which skills give a steady training signal and drop the rest.

New NYU and Amazon paper finds that distilling a few skills that keep producing a useful training signal matches or beats distilling a skill bank up to 11× larger.

Skills are short written tips, like a rule for counting cases, that a model absorbs by learning from a copy of itself that reads them. Picked by topic match, under 25% of them gave any useful signal across 3 Qwen models.

SGUID keeps only skills that help early in training and still help late. With 6 such skills, 3 of 4 models matched or beat the full bank of 30 to 71 skills on math contest tests. A 2nd round with 3 new skills lifted Qwen3-8B from 64.3% to 66.3%.