I generally prefer to run game sessions that run around six hours in length, however that seems to occur pretty rarely now a days much to my own frustration.
The group I used to game with a few years ago preferred to play in marathon long game sessions that would be between twelve to fourteen hours on a Saturday or a Sunday, and much woe to anyone that had life get in the way of their dice rolling and chortles of laughter. You know, things like a job, death in the family, passing a gull stone or contorting a testicle. They thought of themselves as hardcore, and that a game session wasn't real unless you spent the entire waking day sitting in their cramped, cat infested apartment and listened to them argue, fight or run off to the other room for a quickie while the rest of us were either engaged in life or death mortal combat, fighting the GM's overly built NPC's or having our brains try to escape our skulls while figuring out some blatantly illogical mind teaser.
For the last year I tried GM's for a group whose game sessions managed to last around an hour and half on average, with the players more concerned about other thing then coming over to game. You know, those important things like viewing YouTube videos, trolling forums that should not be named, catching up on gossip or texting on their cell phones. On occasion, we managed to run a few sessions that were three hours long, but those were rarities, since getting everyone here on time and starting seems to have been about as difficult as teaching a fish how to play a banjo.
Out of years of gaming, for me five to eight hours is the preferred length of time to keep the game itself flowing as well as the attention of everyone sitting around the gaming table. Anything less and players or the GM gripe how the game isn't moving or the feel like nothing is being accomplished and anything over that, they forget or lose interest in what is going on or get tired of being around everyone and begin to get antsy and argumentative. Of course, all of this could just be an Ohio thing from our complete and total lack of Vitamin D, since the sun has much better things to do then rise and fall over the Buckeye State.
