alt Hacker Newsyep, in my observation the ratio of "having backup processes" to "having periodic disaster recovery drill" is somewhere in the area of 20:1.
Even within the same company. Every division has backup processes, only few actually try to recover the data once in a while...
At least they have a process. That gives you a chance. Often the process itself is good - you didn't test it but the vendors all did and so the data is there - it might be hard to restore, but it can be done by experts after the fact. The drill means you can recover in a "short time" instead of a "long time" (short time can range from minutes to days, while long time days to years)