comment: >
  
  2 hours maximumoigke
context: It really depends on the script. If you have a small story to tell, 90 minutes is fine. If you want to tell 6 storylines in different places, like the last Star Wars trilogy, you'll end up with characters and plotlines that noone cares about. Because you don't have the time to get invested in them.
  I enjoy a film that takes the time to tell a story. It's fine when it's slow or when not a lot is happening. It really gives you the time to become part of that world.
  I probably sound like an old man (i'm in my 30's), but these days most mainstream movies are edited super fast. As if they are afraid to lose the audience when there is no action for 5 minutes. >
  
  I gotta agree, for average movies, yep, 90 minutes seems approachable. >
  
  It depends on the movie. A bad film can drag after as little as 45 minutes and be an absolute chore to finish even with a shorter runtime. But something like LOTR or JFK is gripping enough on its own to keep you invested throughout its 3 hour runtime, since every minute is essential. >
  
  I was once dragged by friends to see the 2nd LOTR film. I feel it could have done with a shorter edit for cinema release, I didn't find it that gripping as a casual viewer.  Then do an extended cut for fans on DVD and later cinema release >
  
  That depends on the subject. A comedy or rom com can be 90-100 minutes and that feels about right. 
  A complex period piece, or a multi part saga like Star Wars or Harry Potter or LOTR can easily go 2-2.5 hours. >
  
  Yesterday I watched the 2h black&white movie "It's a wonderful life" and at the end I was in tears. >
  
  Damn, even OP wouldn't cry about a film being two hours long >
  
  Hard agree. Fell asleep during Gangs in New York around the 1 hour mark out of sheer boredom and the movie's glacial pace. Slept a good 90 mins. Woke up. My wife smiled and turned to me and said you were out quite awhile... looked down at watch, still had another hour to go!!
  Never again.