

It isn’t that key - most backups do work. Backup program creators test that everything works. and there are consultants who can help restore - for a price - in an emergency.
However if you want to restore fast you better have tested the process recently - all the staff needs to have experience in what to do.
If you want to be 100% sure you got everything backed up you need to do a real test as well. That means you regularly tell everyone no working this weekend, leave your computer behind - when you return it will be wiped to factory and restored from backup. I don’t think anyone does this.


My cousin did. He was on track to graduate until he was in the hospital for a month. They let him graduate with his class but he had to go back for a few months to retake the classes that he failed for that reason before he got his diploma.
Other than that weirdness though it unlikely.