Ask a group of people about how long a D&D session should run and I’d imagine you’ll get every answer from ninety minutes to all day. Ask the clock and the answer is two hours and forty nine minutes. About half of all recorded sessions run shorter, half run longer. The single busiest half hour is the one between two and a half and three hours. 18% of sessions end there.
The long game is rarer than it sounds. About 7% of sessions run five hours or more, one in fourteen. In 2000, Wizards of the Coast player survey asked people how long their typical session ran and 28% said five hours or more. Obviously, the two numbers measure different things with the survey asking players to describe their typical session from memory and ours is the recorded length of sessions that actually happened.
Where the long games live is the weekend. Call a session a weekend session if it starts on a Friday, Saturday or Sunday in the table’s own time zone. The middle weekend session runs three hours and the middle weeknight session, two hours and thirty-six minutes (about twenty five minutes of difference, not much). The marathons are where the two come apart. One weekend session in nine runs five hours or more. One weeknight session in fifty does.
The short night, meanwhile, belongs to no day in particular. About one session in seven is over inside ninety minutes, on weeknights and weekends alike. The weekend adds a long tail to the night. It doesn’t take away the short one.