Amazon penalizes a listing that repeats an exact search term in its listing copy (title, bullets, backend, description) more than 3 times — past that threshold the product can be fully de-indexed for that term, meaning it stops appearing in search results for it entirely.
This cuts against the older keyword-stuffing instinct that more repetition means more relevance: past the threshold, additional repetition actively removes ranking eligibility for that term rather than reinforcing it. It's a hard constraint on how Master Keyword List & Listing Scorecard keyword placement should be executed — the scorecard needs to track repetition count per term, not just presence/absence.
Likely enforced by Cosmo (Amazon's Rufus-Powering Algorithm)'s relevance/spam filtering rather than a simple keyword-match model.
Brandon's specific claim: Amazon de-indexes a listing from ranking on a search term once that exact term appears in the listing copy more than 3 times — "the reality is Amazon punishes you when you use it more than three times. So, you lose your ability to rank on it." In one case, a term repeated roughly 20 times in the listing copy triggered full de-indexing on that term — not from low relevance or weak bids, but purely from listing-copy hygiene. Apply: audit listing copy for any exact search term used more than 3 times and trim down to 3 or fewer to restore indexing eligibility.
A keyword only needs to appear once anywhere in the listing (title, bullets, description, or back-end keywords) to be indexed by the A9 algorithm — repeating it further doesn't improve indexing and risks the de-indexing penalty. See Helium 10 Listing Builder for the back-end keyword field where leftover unused keywords should go instead of being stuffed into repeated title/bullet text.
Beyond de-indexing risk, Amazon does not want the same keyword used more than about twice in a single title — a third repetition reads as stuffing rather than optimization. See Amazon Listing Title Structure Formula for where in the title keywords should go instead of repeating.
A stricter, title-scoped version of the general de-indexing risk: per 6 Steps to a Perfectly Optimized Amazon Listing, Amazon is reported to disfavor a title that repeats the same keyword (e.g. 'vitamin'/'vitamins') more than roughly twice, even when that keyword is high-value. Audit titles specifically for this before finalizing, independent of the front-loading covered in A9 Title Keyword Weighting (Position & Phrase Match).