Earlier quoted context omitted.
Another great question is "When did you last try to restore from a backup?" which usually is answered with "It's the built-in tooling, why would we assume it's broken?" or similar. Then fast-forward some months/years, and they try to restore from backups only to realize the backups never actually backed up what they cared about.
my dad told me about this customer that had a server that made automatic backups each Sunday night. The backup script would backup all the data then eject the tape so the manager could put it in the vault and rotate in the other one from the vault. When the hard drive failed, they restored the customer to the latest backup. Which was the tape still sitting in the tape drive in the server. It was from the first Sunday…
Or do you mean the backup process was fine, but they restored from the wrong media, a very old tape that was about to be overwritten, instead of retrieving the one with last-week's copy?