Quality over Quanity - thats one of my favorite mottos =). I post I think an average of 15 times a day or something (you can check my profile if your bored). When I first started these boards, I posted like 30 times a day to boost some activity =). It all varies, if theres a lot of activity and interesting posts I will post more, less > less.
But yea, quality over quanity.