I have a MacBook for work and I'm not sure it has ever updated overnight like it said it was gonna. It's quite annoying because OS X updates (or my work's custom stuff? Idk) are so, so bad. Big, focus grabbing prompts popping up to say I need to update, when I agree to do it, it has to download too (every other system I use just downloads automatically and only prompts about the restart), and it is the slowest OS update to boot!