Q. I've been writing a script for several years now that I just can't finish. I am really tempted to jump ahead and start writing scenes towards the end, going back later to fill in the middle. Do you recommend this method?
I recommend any method that works for you. Especially, any method that gets you unblocked.
I suspect also that you did not take enough time on your story. The best way to come up with a screen story is to tell it out loud, over and over, to anyone who'll listen. As you retell it, you'll naturally revise it, streamline it, embellish it, and play with it. By the time you're ready to write the script, you'll have a "just add water" outline.