I play nothing until a game I'm interested in releases, then I basically marathon it.
My rule of thumb is that when I start a game, I play it every free moment I have until I beat it. Then I chill and wait for the next game.
I'd say this averages out to about 30 hours a month, so 7 hours a week. But it's more like nothing 90% of the time, and 7-10 hour sessions the other 10%.