Some triggers measure "nothing has happened for N days" — `diary.no_entry_for_days`, `forms.no_submission_for_days`, `*.section_unread_for_days`, `*.revision_stale_for_days`.
If we fired those triggers the moment a workflow was activated, you'd get a flood of false positives — every dormant area would trip every "no entry for N days" workflow on day one.
How the buffer works
When you activate a workflow, the threshold is measured from the later of the last relevant event OR the activation time. So a 7-day threshold genuinely has to elapse since activation before any trigger can fire, regardless of how stale the underlying data is.
You can disable the buffer per-trigger in advanced config (`from_activation = false`), but it's strongly recommended to leave it on.