<b>Lastmod only works if you don't lie</b>

<b>Lastmod only works if you don't lie</b>

Google uses sitemap lastmod as a re-crawl hint — but only after it trusts the signal. Sites that touched lastmod on every URL nightly (auto-generated, not real edits) got their lastmod effectively ignored.

Re-crawl response to lastmod change, 28 sites:

— honest lastmod (matches real edits): +4.1 crawls/mo on changed URLs ▓▓▓▓▓▓▓░░░
— blanket-nightly lastmod: +0.4 crawls/mo ░░░░░░░░░░

A 10× difference in crawl responsiveness.

So what: set lastmod from the actual content-modified timestamp, not the build timestamp. A sitemap that cries wolf gets the whole lastmod field discounted.