Everything on the screenplay page must be able to be seen on the screen.
So, when you’re writing, and are puzzled about whether something
should be on the screenplay page, or not, look at it and imagine
yourself in a theater watching this movie. Where would it fit in
Also, always rely on this: People who read screenplays, agents, directors,
producers, production companies, actors, script readers, etc. have stacks
of scripts to read. Therefore, it is part of the screenwriter’s job to strive
to have more white on each page of the screenplay, than black. All
screenplay readers want to be able to “buzz” through each screenplay. And
brevity is part of the art of screenwriting.
I hope this is of help to you.
Donald L. Vasicek
Olympus Films+, LLC
The Zen of Writing (& Screenwriting)