A sitemap rebuilt every morning may give every page today’s date, even when none of the articles changed. That looks fresh in a file, but it does not accurately describe the pages. The sitemap’s lastmod value should represent a meaningful update to the corresponding URL.
Google’s sitemap documentation says it uses lastmod when the value is consistently and verifiably accurate. It distinguishes significant changes to content, structured data or links from a routine copyright-year change. A regenerated sitemap is not automatically evidence that each listed page was revised.
Find the event that sets the date
Ask what your CMS or sitemap plugin uses: an editorial modification time, a database timestamp or the moment the sitemap file is generated. These can be different events. A deployment that rewrites cached files should not necessarily make an unchanged article appear newly edited.
Check a small sample: one genuinely revised page, one untouched page and one newly published page. Compare the visible content, editorial record and sitemap entry. The purpose is to understand the system’s behaviour before changing settings across the site.
Keep an update note that explains the change
For an illustrative example, correcting an obsolete installation step is a substantive edit. Record the correction and verify that the page now shows the intended instructions. That gives the timestamp a real event to represent and helps an editor distinguish it from a formatting-only deployment.
Do not treat dates as an indexing switch
Submitting a sitemap helps communicate URLs; it does not guarantee that every page will be crawled or indexed. Repeatedly advancing dates cannot replace useful content, working links and accessible pages.
If a system cannot supply a reliable modification date, investigate its configuration rather than inventing one. After a fix, recheck the same sample through another publishing cycle to confirm that unchanged pages remain unchanged in the sitemap.