TL;DRRun three compaction passes at T-90, T-30, T-7 days. Each pass throws away 50–70% of the previous version. Final 100 pages should contain only what you cannot recall from memory. Compaction is not summarisation — it is ruthless triage.
Related:
TL;DRPrep notes capture the topic. Answer notes capture the answer. The difference is structure: a prep note is bullets-by-concept; an answer note is intro-body-conclusion in 150 words, with one stat, one case, one diagram cue, one way-forward. Build both — they are not the same asset.
TL;DRPick one chapter. Close the book. Write what you remember on a single A4 page in language a 12-year-old understands. Mark every gap. Open the book, fix only the gaps. That page — never more than one — becomes your T-30 revision asset. Feynman's technique, weaponised for UPSC.