For Decade, the session lasts exactly one hour from when the first player arrives to when the session ends. Then there's about 10 minutes of character advancement and wrapup, so for most players the game will last about an hour (the first person there gets to play more!). I'm being quite strict about this, as the game is set on New Year's Eve and the stroke of midnight is when all the characters kiss and we fade to black for next year . . . .