Use invalidate for routine Akamai purges, it revalidates against origin and can even keep serving stale content if your origin is down. Reserve delete for compliance removals where the bytes must be gone. And after a purge, verify with a fresh request, the purge itself is a one-shot operation, not a standing rule.

Context: Official Akamai TechDocs (purge-cache/docs/purge-methods): Fast Purge supports two methods, and picking wrong is the classic mistake. Invalidate marks cached content invalid; the next request triggers a conditional GET with If-Modified-Since, so the edge can keep serving cached bytes when the origin says nothing changed. Delete removes the content outright and the next request always pulls the full object from origin. Delete hammers origin bandwidth, so use it for compliance or copyright removals. Purge requests also do not persist: the edge executes and forgets.