Case: Honest lastmod cut wasted recrawls 38%

Case: Honest lastmod cut wasted recrawls 38%
A news site stamped lastmod with today's date on every build. Google learned to ignore it.
What we did:
— Pulled lastmod from the article's true content-edited timestamp
— Excluded layout/CSS deploys from triggering a new date
— Verified 200 sample URLs: stamped date matched last real edit
Measured outcome over 30 days:
— Recrawls of unchanged pages fell 38%
— Median time-to-recrawl for genuinely updated articles: 11h → 4h
Run this audit:
✅ Pick 50 random URLs from the sitemap
✅ Compare sitemap lastmod to the page's real edit time
✅ Flag any URL where they differ by more than 24h
Definition of done: 95% of sampled URLs have lastmod within 24h of true edit.