When do you mark a source as checked instead of only linked?

A source-trail question about checked dates, review triggers, and changing official guidance.

A bare source link is often not enough when the source changes over time. For Google guidance, MDN compatibility tables, NHS reviewed pages, or EUR-Lex consolidated texts, I want to know what was checked and when. I am leaning toward a small source freshness note: checked date, source type, and review trigger. Do you add that note only for high-risk pages, or for every page where the source can change?