It would be easy to adjust the algorithm like that. However, to strive forcompletely accurate numbers is a waste of time, IMHO, since like I said, you cannot know what will happen during the operation anyway, so you have to work with some sort of time-window and make your estimate be based on that.
It reminds me of this : http://imgs.xkcd.com/comics/estimation.png -- Adrien Destugues / PulkoMandy http://pulkomandy.ath.cx
