Hi,
Pokertracker keeps counting the hours when you sitout from the tables (at IPoker, dont know other sites).
What i mean is, if you play one hour straight, and than sits out for 10 minutes, pokertracker will say that you played 1.16 hours, when in reality you played 1 hour.
It makes a big difference in the long run, specially when u wanna know your $/hour.