If you're optimistic you call it the "vacation or lottery" factor - if Bob wins the lottery tonight, will our shit still work tomorrow?

And if the answer is no, well, then Bob just got Hotel California'd and can check out but can never leave.

Help Bob; help yourself.

We call it the HB3 (Hit By Bus Binder). Aka keep a document containing what to do if someone of your team gets hit by a bus.