I would think that any facility that requires electricity would be a bad choice to keep anything that you'd need in a major incident.

First because if it's a natural disaster there's a good chance that the power will be off, secondly, if it's something like a riot or some other social upheaval I can't imagine the folks at the local gym sticking around so you have access to your locker. Same with a private mail facility. If you worked at such a place would you open up during a hurricane, flood, fire, riot, etc. ?

It's a good question.