Something I've found interesting since, well, I guess since I studied screenwriting lo these many moons ago, is the rigid devotion structure and length of films. From a commercial side, I get it. If movie's are much longer than two hours, they get less showings every day, and so less $ taken in.
From an artistic standpoint, I find it kind of annoying. I mean, if children can read a 900 page book like Harry Potter and the Order of the Phoenix and be begging for more, I don't see why they can't sit a little longer for a movie. I guess it's a cultural thing - it's been how Hollywood and film companies and filmmakers have functioned under it for a long time. I suppose it's changing with us binge-watching seasons of TV shows over the weekends, etc., although that's a different medium with it's own constraints. With film, the 120-ish minutes running time is still kind of a holy thing. The LotR films broke it, Avatar broke it, some non-genre epics have broken it (to varying commercial and critical success). But generally, it still prevails.
Now we're in the age where a movie is split into multiple movies, which is another kind of weird, which brings us back to the commercial side of things - Jackson's three Hobbit movies made waaaaaaaaaaaaaay more for the studios than a single film or even two would've. Commercially successful, critically? Not so much.
I guess what I'm really saying is I want to watch Boyhood this weekend (2 hours, 45 minutes), chase it with some Pixar and Disney shorts, then finally cue up the 5 hour Che Guevara biopic and try and figure out how much longer it is until the Daredevil series comes out on Netflix.