I have a ~160GB (maybe 250?) external USB drive that is labeled "Windows Updates". It sits on a shelf waiting to be plugged into whichever machine "needs" updates (I don't let my machines "talk to the outside world" so *they* can't "fetch" the updates using the normal mechanism)
Consider each time you "updated" a machine, you went through the trouble of downloading those updates -- and then DISCARDING them after they were installed... :<
(I build computers for local non-profits; I can't afford to tie up my internet connection 24/7 trying to re-download the very same files that I just used to "update" the last machine that I built for the NEXT machine I'm building! And, the machine(s) after that...)
And, not have to be reliant on MS's servers being "up", your inet connection staying up, etc.