Charles JonesAny count, size, or claim about what exists that arrives from somewhere other than a fresh measurement is treated as a pointer — a place to go and look, never a fact to act on.
It gets re-measured before it is used, and always before anything is built.
Where the rule came from
Numbers age quietly. A figure written into a handover was true when it was written, and the file gives no indication when it stops being true. The failure is not that the number was wrong; it is that nothing about reading it tells you to check.
How it shows up in practice
When a re-measurement disagrees with the inherited figure, both numbers get reported. The old one is not silently corrected and not silently adopted — the difference is itself a finding, and usually the interesting one.
Every figure published on this site carries the date it was measured for the same reason. The numbers on the homepage were measured on a stated day. They are honest and they are dated, which is not the same as current.
Why it is on a public page
Because it is checkable. The sitemaps that back the page counts are public; the PageSpeed score can be re-run by anyone. A claim that names its instrument and its date is one you can go and disagree with.