90 mins, smoke, hour, food, TV, 90 mins, smoke, 90 mins is my general ritual.
Problems - the games get crap after midnight, I like to see the sun during the daytime, I'm nocturnal so when I'm at my best all the fish have gone to bed.
How long is everyone's brainfreeze threshold (How long does it take before you find yourself playing bad on autopilot)? for me it's about 3 hours and then my mind starts sparking out.