Backups you have never restored
An untested backup is a strongly held belief.
The backup ran nightly for two years. The files were there, the sizes looked plausible, and the monitoring said green every morning.
The first restore failed, because the database dump had been written with a flag that excluded the largest table, and nobody had ever read the dump. The check had been asking whether a file appeared, which is a question about the backup job, not about the backup.
Restore it somewhere. On a schedule. Then check the restored copy carries a row you wrote yesterday. Existence and fidelity are different questions and only one of them matters at three in the morning.