The size of art changes the way we experience it. (By size, I mean length or running time, and by art, I mean all forms of artistic expression.) I don’t know if this is a good thing or bad thing, but it’s a thing.
Further: It’s not just that we feel differently about a three hour movie versus a ninety minute movie. It’s that knowing there’s an hour left changes the way we feel at the 120 minute or 30 minute mark.