Most sitemaps give each page a <lastmod> date. Link Signals compares it with the date it saw last time and skips pages that haven’t changed. That makes later checks quick, but it only works well if the dates mean something.
<url>
<loc>https://example.com/pricing</loc>
<lastmod>2026-10-08T00:00:00.000Z</lastmod>
</url>Check yours
- Open the sitemapOpen its address in your browser and look for
<lastmod>lines under the page entries. If a sitemap index lists several sitemaps, open one of them. - Reload it a few timesIf the dates move to the current time on every reload, they aren’t real modification dates.
- Change one pageEdit and save a page, then reload the sitemap. That page’s date should change and the others shouldn’t.
What you see and what monitoring does
| What you see | What monitoring does | Effect |
|---|---|---|
| Dates change only when a page changes | Reads the changed pages, plus a rotating slice and a monthly pass. | Fastest, and the cheapest on your allowance. |
| No dates at all | Reads every page on every check for sites up to 20,000 pages, and rotates through larger ones. | Correct but slower. |
| Every date is always “now” | Sees every page as changed, so reads everything each time. | Correct but slow. |
| Dates that never change | Doesn’t read a changed page until it comes up in the rotating slice or the monthly pass. | Changes are noticed late. |
Why the dates matter
Monitoring reads a page again when its date in the sitemap differs from the one it recorded last time. The comparison is of the date as written, so any change counts, whether or not the page itself changed. A page with no date at all cannot be skipped, so monitoring falls back to rotating through the site instead.
Dates are also used when a site is bigger than your plan reads. A scan then reads a sample: the homepage, the most recently changed pages and an even spread of the rest. “Most recently changed” comes from the dates in the sitemap, so real dates help a sampled scan look at the pages most likely to have changed.
Common reasons dates are not trustworthy
| What causes it | What you see | What to do |
|---|---|---|
| A plugin, theme or build step stamps every page with the current time | All dates move on every reload of the sitemap, or after every deploy | Look in the SEO plugin’s or generator’s settings for how dates are produced. Dates should follow when content was last edited. |
| The sitemap is generated without dates | No <lastmod> lines at all | Nothing is wrong. Monitoring reads every page on every check for sites up to 20,000 pages, and rotates through larger ones. |
| Dates are set once and never updated | Edited pages keep the date they were published with | Changes are noticed late, when the page comes up in the rotating slice or the monthly pass. Fix this if you can. |
| A cache sits in front of the sitemap | A page you edited does not show a new date straight away | Clear the cache and reload. If the date then changes, the sitemap itself is fine. |
A worked example
A small business site has 400 pages. Its SEO plugin writes the current time into every date, so the sitemap says all 400 pages changed a moment ago. Each monitoring check therefore reads all 400 pages. The results are correct, because nothing is missed, but each check takes much longer than it needs to and puts more load on the site.
After the plugin is set to use the date each page was last edited, only the pages edited since the last check are read, plus a rotating slice and the monthly pass. Checks get quicker and the same links are flagged. Nothing about what is found has changed, only how much work it takes to find it.
Dates do not hide anything
A page whose date never changes is not exempt from checking. Roughly every 30 days monitoring does a full pass, and each check reads a rotating slice of the site regardless of dates. That slice is also compared as a search crawler would see it, so a cloaked link can still be found on a page that never appears to change.
Questions
Do sitemap dates matter for a one-off scan?
Only when your site is bigger than your plan reads. Then the dates help choose which pages are in the sample. For a site your plan covers in full, every page is read whatever its date says.
Do I have to fix my dates to use monitoring?
No. Monitoring works with any dates, or with none. Accurate dates make checks quicker and changes noticed sooner.
How do I know which pages were skipped?
After a check, the figures for pages read and pages skipped show how much of the site was read again. A low number after you have edited several pages is a sign that dates are not updating.
What you are told when you load the sitemap
When you load a sitemap, before you run anything, Link Signals reads its listing and tells you how many of its pages say when they last changed. This is free: only the listing is read, and nothing is checked. A sitemap with every date lets a later scan tell which pages are unchanged. One with none, or only some, means those pages are read again each time.
Add it and the first check shows how many pages were read and how many were skipped.
