I dont usually time how long I play for I just play until like 100 + points if I have nothing much else to do. And 100 can take a long time for me to get to...
I'm not sure i even want to admit to myself my longest gaming-spree was.
Not as bad as some of you, but still a lot longer than i think i probably a good idea.
I remember when I first got my new computer I started tf2 and was amazed at how well it worked. When I got home all I remember was playing at like 3:30pm, it was dark outside, and then it was light again.
although I don't think that really counts as a single sitting seeing as during that time I watched a movie and went into town. I guess actually playing, I've done no more than 3 hours on TF2.
Sad to say, on wow I leveled from 67 to 70 in one day. After I got to Northrend I just couldn't stop playing >.<
That was 13 hours in a single sitting (excluding 2 10 minute breaks for lunch and dinner).