Does the length of the episode have any bearing on this? watched the whole series of minigoddess(they are like 7 minute episodes), followed by random anime over the time frame of 14 hours... was hosting an anime marathon and people just picked out what they wanted to watch from either my collection, or what other people brought. I believe we finished up by going back to my dorm room and watching some more anime to finish up whatever series people got hooked on... so 18 hour anime marathon essentially with 2 small breaks when I got too hungry to continue... Since there was food in there at the start... only left the room once give or take a bathroom trip or two...
I was president of the Otaku Jinrui - The UNL Anime club for a couple of years... we had 12 hour anime marathons at the end of every semester on Saturdays... occasionally they started a little early and went a little later...