This seems to vary quite a lot from what I´ve seen so far. Some people have the main loop done in 5 mins (how the hell can they do that so fast?? ;-) )and then arrange around it for another 45 minutes and they have a new slamming technotrack, others take their time and wait for inspiration to come and have 5 or so unfinished tracks at a time.
I usually have the main loop done in around 15 minutes, then I play around with the effects and filters a bit, and then start another one. the next day I´ll return to the first and start changing things that didn´t bother me the day before. Usually I have the whole track done in about 2-3 days. Some times it happens though, that although a track is almost done I start losing interest or forget about it. Oh well, guess everyone has his bad habits ;-)
So basically I was just curious, how much time do you devote to a track before you move on?