In a previous life, we passed around virtual machines rather than doing paperwork. Paperwork is to be sure you have a plan to solve the explosion-and-revert problem.Managing machines instead of paper allowed us to include a process for doing an immediate revert on explosion (;-))
The VMs we passed around were Solaris zones, so they were very lightweight. If I wanted to apply an emergency patch to production, I first applied it to an image, put an instance on pre-prod, a physical machine, and varied it into test. After the smoke-test, I varied it into the pool on the load-balancer, and watched it closely. If it fixed the problem and didn't explode, I put lots of instances on the production physical servers and put them into the load-balancer, quiescing the un-patched instances but not erasing them. If the patch blew up after all, I could revert to the previous buggy release as fast as the load-balancer could disconnect people. Not quite as fast as doing an atomic change on a single server, but fast.
This is a minor variant on some old unix norms: 1) you aren't prohibited from doing even silly things, as prohibitions will keep you from doing something brilliant. 2) You can do anything, but you can't hide what you did, 3) you can change things atomically while running, and 4) if you do something dumb, you can revert it immediately.
The process is a variant/predecessor of ITIL, with pre-set apply and revert steps for emergency changes, which are the high-value part of the whole ITIL change process. Non-emergency changes were a little more heavy-weight, as we tested the patch in an instance in QA, then did a simulated UAT overnight (it was automated, but exceedingly slow), reviewed the results and then the de-facto board decided if we could release the image to production, QA and dev. Your paper-oriented CAB does approve all patches to QA and dev, right? I'll bet they missed that part (:-))
I did once have a customer where I had to do paper-based CAB approvals, but that was because we weren't funded to have a proper dev, and had no QA at all. As you might guess, we still had at least one fiasco. I shortened the contract as much as I could without doing a no-bid in the middle.