Ask a board whether the website is backed up and the answer is almost always yes. Ask when somebody last restored one and the room goes quiet. Those are two very different things.
Where the backup lives matters
A backup kept on the same hosting as the website is not much use. If that server has a bad day, or the account is closed for an unpaid invoice, the backup goes with it. It needs to sit somewhere else entirely.
How far back does it go?
Some hosting keeps one backup, overwritten nightly. If a problem started three weeks ago and nobody noticed, every copy you have contains the problem. Keeping several months of weekly copies costs very little and solves this completely.
Test it on a quiet Tuesday
Twice a year we take a backup and actually rebuild the site from it somewhere private. It takes an hour and it is the only way to know the backup is complete. The alternative is finding out on the day the site is gone, which is the worst possible moment to discover that the file was empty all along.