This is a tough question to give a simple YES or NO answer to. In fact, I think it is impossible to make it such a black and white situation.
For some, the books may work…for others, not at all.
A lot depends on what you want to do. Do you want to be a screenwriter or an auteur?
If you want to strictly be a screenwriter (i.e. writing with hopes of selling your scripts to a studio, or producer, or director), then the books are going to be of some help to you as far as getting you on track with the so-called “proper format” that the “industry” requires.
Personally speaking, I feel that beyond helping the reader get some good ideas on screenplay structure, or format, I don’t know that books really help all that much.
Keep in mind that when I am talking about structure and format I am not talking about story content or structure. All that point by point, 3 act formula stuff is just bullshit. I am talking about the page structure and format.
Also if you are wanting to strictly be a screenwriter, reading screenplays for films you are familiar with can be helpful, as well (like someone already said above). But, be careful…because most
published screenplays (i.e., those in book form) for films you are familiar with are generally just transcriptions of the films the way they appear on screen (complete with camera movement descriptions, etc.) and that is NOT the way the studios want submitted scripts to be written. They don’t want any camera directions, and the like. Those decisions are up to the director. When possible, try to track down copies of the original scripts and not those that are officially published in book form.
Now, if you are wanting to be an auteur…entirely writing and directing your own stuff… NO RULES apply! Do whatever you want, however you want. Just follow what you feel.
That’s my take, anyway…