How much is winrate affected by how long a session you can play?

[lightfungus]

I always couldn't understand how people played so many hours straight....then I started playing at a casino, and would easily see 6-8 hours pass by without a drop of the hat. The only reason I didn't play longer sessions was because I had a job and I couldn't put all my time into poker. But playing live for 12 hours was easy, and I did it on the weekend once or twice. Online poker just doesn't have the entertainment and social interaction that live does; time goes by much faster when you are having fun.