Extremely Fluffy Fluffy Thing posted:I think our IT guys run a back up every weekend, or possibly every night, but the number of times we get a message to say it failed is amazing!
Unfortunately a lot's going to depend on the details of the backup policy and its implementation.
It's the same with security updates: in theory, Systems post-XP should be patched, but in practise many people have been slow to do so... 
Speaking personally, my company's backup tool seems to be fine for my own day-to-day work, but I've colleagues who've had big problems with it. My own problems have been down to more systems-related data, which even IT assumed was being included in the backup process, but wasn't in practise. 