I think it was with Gintama when I was sick... I watched like 25-30 episodes straight... I never skip ops and ends so it was like... 9.5-11.5 hours... Anyway, I remember that I watched those 202 episodes in a week...
I know one time I spent virtually the whole day watching a show. I probably watched like 40 episodes. I was home alone so I didn't do much else. :P
Usually I won't watch longer than an hour or two before I feel like I need to get up. :)
Well, all two seasons from Kyoukai senjou no Horizon (2 × ~ 5,2 hours) and all episode of Oda Nobuna no yabou (1 × 5,2 hours) = all in all about 15 hours in a day - And that was before a and half week ago.