I'm on several times a day - when I'm at work, I open it and leave it minimized, checking it periodically and occassionally leaving a post (as I'm doing now!). When I'm at home, I leave it open pretty much all the time - my kids hate it, cuz when I let them go on the computer, I make them leave my PF tab open, and check in about once every hour or so!!!
Needless to say, my kids think Im pathetic!!!