WordPress uses scheduled tasks for work such as publishing a post at a chosen time. With the default request-triggered mechanism, a quiet site may not run due work at the intended minute. (WordPress WP-Cron documentation ↗)
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Checking whether the scheduled task actually ran
Illustrative times: a post is due at 09:00, but the next site request arrives at 09:17 and triggers WordPress’s due-task check. The post may publish during that request, so the monitor request itself can cause execution. Record both the request time and actual publish time before diagnosing lateness.
A stored time is not an execution receipt
For time-critical publishing, compare the scheduled time with when the page actually became publicly available. The date shown on the article may reflect the scheduled time rather than prove the job ran then. A separate system scheduler can trigger due tasks without waiting for a reader visit.
Record the trigger as well as the result
Schedule a test post and compare its expected time with an independent log and the public appearance. A visit used to check the result can itself trigger work on some setups. Keep that request time separate so it does not hide a late launch.