I know I generally keep a followup on threads I've posted to, either aging them out after a while, or when there are just too many replies that start to have little relevance. But like everything else, it's a case by case basis, not a blanket statement .
I tend not to keep up with threads that don't pique my interest, such as the current Load Balancing
Personally, I think it's important to keep up with threads you've particpated in, for a number of reasons. If for nothing else, to see if some one has logically disputed your presentation, and (to use a bit of southern speak here) learnt you somethin'.