(Oh shit, everything just went down, turn on the generator, go plug that printer and laptop in, and print off all the reports of where we were from the offsite/offline/whatever backup).

What did they do before computers?

Failing to plan is planning to fail and all.

I like the idea of monthly planned downtimes where possible so people don’t run around like a headless chicken when things go down. No different than a fire drill.

If they did, I would expect their employees to be out of practice with such methods since they weren't working that way day-to-day. Unless they're running regular "all computers are down"-drills to keep their employees sharp, downtime was probably inevitable.