[peterwwillis]

If you're making a big change you first cut a CR and get approval of any teams involved. At change time, everyone knows they need to be on-call if something breaks, preferably in a live chatroom.

The rest of the time devs should just deploy when they think the code is ready and have tested it on a like-production box. They then manually verify the change worked. You use automated monitoring to ensure when something does break you are notified immediately.