How often should you actually test a restore?

A backup is only proven once you've successfully restored a real file or mailbox from it. Test at least twice a year, and after any significant change to your backup software or storage. Pick a real but non-critical file so the test means something, and time how long the restore takes, not just whether it worked.

Coach's tip: put the test in the calendar as a recurring task with a named owner — "we'll get to it" backups never get tested.