A lot of writers really get all bent out of shape and neurotic about the level of control with the words on the page. In most cases, I look at this as a writer who’s inner critic has run amok. This is one of the many ways to self sabotage.
There was one girl in my class in film school who really had very little grasp on story or character but would spend an exorbitant amount of time on the details of words she chose within phrasing, etc. She would give really detailed notes on dialogue and would do a ton of line edits. I would laugh at her notes because the line edits don’t matter if your basic subject matter is odd, the story doesn’t make sense or there’s no character.
The script has to be in a good enough place to get the line edits, otherwise it’s a complete waste of time. That’s why it’s self sabotage. Because, if you have a too-precious love of all the dialogue coming out of your Son character, but that character isn’t right and later morphs into a much younger Daughter character to better serve the A story and the protagonist’s character arc, it won’t matter that you loved your precious dialogue. It’ll all get rewritten anyway.
The scoop on line edits is this – don’t worry about your line edits until all other elements in your script are in place and working to best effect. My feeling is that you shouldn’t be spending your time going into scenes and spending hours doing detailed scene work until you know you’re going to keep that scene. If you still need to do any rewrite work on any larger script component – the A story, any B or C stories, character arc, theme, tone, pacing, genre, etc. – the truth is that your scenes will probably still be changing. If your scenes will change, you’ll lose a lot of that precious dialogue anyway, and so it makes no sense to go in and do detailed line edits when your script is still in flux.
I look at line edits as a polish. Once every element in your script is locked and working to best effect, you’ve hit all your beats, the stories and character arcs all work well together, your theme, pacing and tone are all working together, then you can go into each scene and punch the dialogue and really delve into the subtext and nuance. That is the time to go and do that level of work.
90% of the scripts I read aren’t anywhere near that level of readiness. They still have major story and character components that aren’t working. Until your major story and character beats are fluidly working, don’t worry so much about your lines. It goes without saying that if your larger beats aren’t working, then the lines themselves probably aren’t working all that well anyway and most of it will get rewritten.
So, don’t stress out too much about the words on the page until the story is at that level. Write to the basic beats of the scenes, make sure the beats are all adding up to what you need them to, and then later on go back and do the line edits.