The shortest run time I can remember attending was 'For Colored Girls...', which lasted 70 minutes the night I saw it, but was said to run 73 minutes. I was not annoyed, to be honest, because I was bored by much of it, despite the great reviews. Living in NJ but working in NYC, I would only see a show that short on a work night; I felt it was too short to spend hours traveling to and from Manhattan. Although I no longer live in NJ, I still have an issue paying Broadway prices for short plays. My solution is to pair a short play with a longer play on a two show day, and get the cheapest seats I can get for the short play.
I admit that I have already thoroughly enjoyed Lifespan and American Son (I paired the latter with Torch Song); however, I still feel that these short plays -- and i include Doubt and especially ADHP2 in this categorization -- lack 'texture' because they either don't take the time to let us know much about the characters (if familiar with ADH, that was not an issue) and / or their focus was too narrow, even if it was a substantial topic.
For example, wouldn't you like to know more about Daniel Radcliffe's background in Lifespan (OCD, ADHD, Genius, all three? or more about the the parents in American Son? or have met the character of the son? I would. Oh, well, just the ramblings of a madman.