It depends, can you only play one game during the session? If that's the case probably not more than a day, but if it's multiple games I've stayed up for about 4 to 5 days straight during one spring break while I was going to High-school, it was one hell of a LAN party. Mind altering substances and plenty of Bawls were involved.
I'm pretty sure that guy was snorting cocaine past the third day if not the entire time.