writing: avoiding formulas while making the work better

Dear Sally,
I have come across a question which I think could be of interest in this forum. I am currently in a phase of re-writes on a screenplay and am trying to put it to a rigorous evaluation for improvements which has included trusted reader feedback as well as my own honest intellectual and gut evaluation.
There are so many axioms and formulas one runs into in terms of prisms with which to look at your writing. Some seem to be of value ( that your central character should in some way be changed by his or her journey in the film) and others seem kind of ludicrous (you must have a plot point twist on page 15). Some of these axioms (example: that your "hero" should be thrown hurdles in every scene to overcome) seem to also come from a very male viewpoint and less relate to the subtleties of the best a female screenwriter can bring to her work, although they seem to be somewhat translatable into this realm and may thus have some value. I am interested in making the work better and following important common sense guidelines while also NOT being a slave to formulas that are most likely at the root of why there are so many bad Hollywood films out there.
I am wondering when you get to the phase of reworking your screenplay, tightening and polishing the work, sharpening the conflict etc, making individual scenes stronger, what standards or processes do you use to look at each scene and the story arc, and how do you judge the draft and work to improve it? Also are rewrites important to your process and do your screenplays change a lot from first drafts? If so how and why?
Once again I thank you for sharing of yourself and your process in this forum.
My best,
Mary H.