One of the things that keeps viewers viewing is a constant increase in the dramatic tension of a teleplay.
That means you have to do more than just drop your hero or heroine into a jam and then help him or her get out of it. You’ve got to keep piling on the woe.
Over the past several years I’ve noticed a running battle on all Message Boards, Bulletin Boards, Facebook Groups, you-name-it about screen and/or television writing. That battle is about how much to describe the action and settings in your script.
I can’t speak for feature films (although my theory there, which I’ve stated in other writings, is that everyone might as well emulate Shane Black, the most successful spec script writer/seller in history. Read something he’s written and then do the same), but I know television.