It's a cool idea, but spending an entire day at the theater like that can be exhausting. It's not like watching a movie while sitting in the comfort of your own home, where you can pause the action and take a break. Sure, there will be some intermissions if you go to the theater. But the sensory experience of the theater screen and sound can be kind of overwhelming.
I saw a couple of movies in the theater in one day a few years ago. IIRC, it was the first Transformers in the afternoon, and Harry Potter that night. By the time I had seen the second film I was kind of wiped out. To me, seeing 6 films in a row like that would not be enjoyable. Especially when the film you really want to see is the last in the marathon.
