Nobody tests the backup

Everyone has a backup. Almost nobody has tried to restore one.

The hosting says "daily backups included", there's a green tick in a dashboard somewhere, and everyone sleeps fine. Until the day they need it.

Then you find out it has the files but not the database. Or it quietly stopped running in July and nobody looked.

A backup you've never restored is a guess.

Once a quarter, restore the whole thing to a staging copy and time it. However long it takes, that's how long your shop is closed when something breaks.