The irony is that after all those years, we still dont find a optimal way to find out - when it is a good time to annoy a user about update decisions. Do it during the system start up phase? Do it before they go into a break? Do it upon return to the system, when work was already interrupted? Do it shortly before shutdown?

No, annoyia be praised. It must be when the user has focused for longer then 5 Mins on something.