Depends on the Game, i Loved the new "Stalker" but it was a short experience, i took around a week to completely the whole game. Dayz i never stopped playing. I have more then a real Life year in Playtime. I Guess this will never end.
If I have the time, I can play 10+ hours without realizing it if it's a good game. But I'm mostly limited to like 3-4 hours because of work. Adulting sucks.
Really depends on the day. If the mood strikes 2-3 hours at a time. I can get restless so even if I'm in the mood to play I have to get up and move around after a couple hours before going back to it. But other days there's just no interest; sometimes I'm even bored with nothing to do so I attempt to play something and end up turning it off 5 minutes in.
It depends on the game, weather and the amount of time I can afford and want to spend on it. It can range from a few minutes to a few hours or the whole day if I'm in the mood. Sometimes I play a lot, sometimes not at all for multiple month.