I think that the most movies I ever saw in a theater in one day was when I was an adult.
It was during the 1970s. I was back in Norfolk, VA for a publicity gig, and I had a totally free day; didn't know anybody in the town. So, I took a cab to this multi-plex and saw 3-4 movies. One of them, I know, was the James Bond movie, LIVE AND LET DIE.
I even paid to see each one, then I took a cab back to the hotel.