Overwriting has always been an issue for me, at least when it comes to first drafts. I tend to put a lot more on the page than is probably necessary, which of course, increases the number of pages.
Case in point – while progress is moving along nicely for the pulpy adventure spec, and I’m faithfully adhering to the outline, scenes throughout the first act are running longer than expected, so the inciting incident will be occurring somewhere around 10 pages later than anticipated.
If things continue at this rate, I may end up with a script that’s somewhere in the neighborhood of 140 pages, which is way too long.
Keep in mind that I don’t make a point of strictly adhering to certain feline-influenced rules/guidelines of a “THIS MOMENT IN THE SCRIPT MUST HAPPEN ON THIS PAGE” nature; it’s really more of a suggestion.
The good thing is that I can just keep pushing forward, knowing there will be some major editing and rewriting in store when this draft is finished. It’s a lot easier to go in and cut, as opposed to scrambling and struggling to add in material. And as evidenced by past behavior, I’ll probably continue to occasionally go back and tweak something I don’t see as sitting right.
For now, the very-helpful process of plotting out the beats of a scene and writing them as such will, but it wouldn’t be surprising if a subconscious effort to tighten things up a little begins to develop.
One brief sidenote – I’ve been making a real effort to reduce the amount of time spent with casual netsurfing and replacing it with actual writing. It’s made quite a difference, and the results have been most productive. I heartily recommend it.
Maximum Z 
I too write way to much. My plan is to write better but shorter action lines and less dialogue. I feel that will preserve the context of the scene if dialogue is changed later.
A good approach. The key is learning how to say more with less for the entire script. Good luck!
I strongly recommend that beginning writers study haiku for a couple of months under a teacher. Haiku teaches economy of words better than anything I know (other than tweets!) Tight writing is good writing.