Windows only ignores this when there are critical updates, which, evidently, every update usually is. So it's not so much windows messing with the time-space continuum, just messing with your head. Your best bet is to choose to let it download and have you choose when to install it, this way you can do it at your convenience. If you see updates going again and again, but failing, next time the update comes up, click expert, and uncheck the updates that don't work. Before you close the window it'll ask if you really want to not install these, check "Don't pest we me with these bleeping updates" (or something like that) and click OK, and they won't bother you any more.
And as for the estimates, Microsoft never seemed to good at math...remember what happened to windows ME?