Backups you have never restored do not exist
We start every new engagement by asking when the last restore test happened. The honest answer is often never.
A backup job that reports success only proves that a file was written. Restoring it into a fresh environment proves that the data is complete, the credentials still work and the procedure is documented.
We schedule restore tests every month for our support clients and record how long they took. That number is the real recovery time, whatever the contract says.