Well there are only four lap counting endurance races. It mainly depends on what car you are driving. So far I have only run any of them in the FGT and my lowest time was around 1 hour and 30 minutes I think... highest being around 2 and a half at Indy. Suzuka will take over 4 hours in an X1. Hope that helps.
Suzuka took my just over 6 hours in the HKS CT230R '08.
Indy took me about 2 hours 21 Mins in the Toyota Minolta.
Don't remember the others but I hope this helps.