Google's John Mueller spoke a bit more about when you should update the date in the lastmod tag in the XML sitemap file. He said on Twitter if you are "providing something new for search engines that you'd like reflected in search," then update the date, if not, then don't.
John said, "Are you providing something new for search engines that you'd like reflected in search? If so, flag it. If you're just changing the timestamp in the footer, sure the page has technically changed too, but should that be prioritized -- probably not."
Here are those tweets:
Are you providing something new for search engines that you'd like reflected in search? If so, flag it. If you're just changing the timestamp in the footer, sure the page has technically changed too, but should that be prioritized -- probably not.
— johnmu is not a chatbot yet 🐀 (@JohnMu) February 24, 2023
John added, "The issue is more that some CMS's / servers set the lastmod to the current date/time for all pages. This makes that data useless. Good CMS's setting it thoughtfully, even if not always perfect, is much more useful."
As a reminder, in 2015 Google said they don't really use the lastmod date but then changed that in 2020 they said they do. The current Google documentation says, "Google uses the lastmod value if it's consistently and verifiably (for example by comparing to the last modification of the page) accurate."
Microsoft Bing recently said the lastmod date is critical and provided super useful stats on how people update the date:
- 58% of hosts have at least one XML sitemap.
- 84% of these sitemaps have a lastmod attribute set.
- 79% have lastmod values correct.
- 18% have lastmod values not correctly set.
- 3% has lastmod values for only some of the URLs.
- 16% of these sitemaps don't have a lastmod attribute set.
- 42% of hosts don’t have one XML sitemap
Forum discussion at Twitter.
