I've noticed since the big update (Anniversary Update), the default setting is a sane "after hours" range of 9pm to 7am on a fresh installation. So, it seems they are improving and are attempting to avoid situations where you're at work in the middle of the day, step away for coffee, and come back to find an update/reboot cycle has wiped out your hard work. I was pointing out the setting for the OP because either he hasn't updated far enough to get the sane default, or he's somehow changed it without knowing and needs to fix it.
Well, that's a lot better than the nagware that used to run during our first-thing-in-the-morning calls 3 or 4 years ago. Hopefully corporate IT doesn't screw it up (of course looking it down, fully screwed).
I still like the Mac's unobtrusive "get it tonight after I shut down" option, though :-) (or Ubuntu's "I'll get it when I'm good and ready", but that's not a system for worker bees)
