I spoke to a group of aspiring screenwriters at the Toronto Film School today and as I was leaving, one of them asked me, "Syd Field or Robert McKee?" I replied, "Aristotle."
Whatever Syd Field, McKee or all the other cats making a fortune writing how to write a screenplay books have to say was said 2500 years ago by Aristotle.
What I told the screenwriting student was that it would be better to read 100 screenplays than Syd Field. Or at least read a few screenplays BEFORE reading Syd Field. The problem, and this is based on reading scripts for the Toronto Public Library for 2 months as part of my screenwriter-in-residence gig there, is that people ONLY read Syd Field and think that's all there is to screenwriting. (I'm not saying Syd Field or any of the other gurus even make this claim, but it's probably easier to read one copy of Screenplay than 100 screenplays.) Then these aspiring writers start writing fill-in-the-blanks scripts. Look, isn't it obvious that writing a good screenplay this way is like trying to paint the Mona Lisa using a paint by numbers kit? (It's sort of like da Vinci, but I doubt it's worth much.)
It's really hard to write a good screenplay. Accept it. Embrace this truth. Recognize you are aspiring to winning the creative lottery.
If it was easy, then everyone would do it and successful screenwriters would be a dime a dozen. How many do you know? See? It ain't easy! And even if it is--say you're massively talented and can't help writing award-winning scripts unlike the rest of us mere mortals--you still have to have SOMETHING TO SAY.
Maybe this is self-evident, but after reading a few of the Toronto Public LIbrary's submissions, I think it bears repeating: without a point of view, a personal perspective, something that you need to get across to the world about the human condition or whatever you're passionate about, no matter what you write will be a waste of pages.
If you do have something to say, if the passion burns off those pages, then you can pretty much break any rule Syd Field et al ever came up with, (though not Aristotle, I daresay.) And your script will still be readable and generate interest from someone. They're not going to toss it out because you haven't had a first act turning point by page 28. That kind of stuff can be adjusted, if necessary. But what no one can do for you is give you something to say.
Read screenplays, live an interesting life, be introspective about that life and maybe, just maybe, you might have something to say that is best said in a screenplay. (Remember, they were writing great scripts long before Robert McKee started making a fortune selling books and seminars.) It's worth doing, but don't expect this to be an easy thing to do. If you read 100 screenplays you probably won't have to read Syd Field at that point. (And since you can read 100 scripts for free off various internet screenplay sites, you'll save some money for your post-draft steak dinner--my personal reward to myself.)