I am really trying to do a good outline, even if it makes me late with actual page count. When I wrote my first screenplay, I didn't outline nearly enough, which meant I went through so many structural changes that I probably wrote the equivalent of about six screenplays worth of words. But once again, my acts get lighter and lighter as I go on:
Act 1 - 13 scenes
Act 2A - 11 scenes
Act 2B - 9 scenes
Act 3 - 6 scenes
Maybe I should just bite the bullet, start writing, and hope something comes to me. Anyone have any sage (or non-sage) advice on beefing up Act 3 in the outline stage? Thanks!

Are you working with a set page count that equals one scene? Because scenes can run many pages or you can have more than one scene on a single page.

I'd say to just run with it. So much becomes apparent during the writing process and maybe you'll find that extra "beef" for the final act.

Outlines actually seem to slow me down because I find myself trying to conform to them when both my sanity and my story would be better off just "winging it" and see what happens. If you really want an outline though, I'd recommend not worrying so much about scenes as length. If you have 11 short scenes in Act 1 and 6 long scenes in Act 3 they could still balance out to about the same length.

Thanks for the advice. No, I don't really know how long most of my scenes are going to be yet. I guess I just feel like Syd Field and Blake Snyder are peering over my shoulder and shaking their heads over my diminishing scene counts. At least this time I do have a pretty solid story-line, so I guess it's time to do the hard part.

Even if it does turn out short when you've written it, short Act 3s are fine as long as it's not an action script, when there's normally an extended action sequence where things are wrapped up and the bad guy is vanquished.

If it is an action script, then a few of those scenes can probably balloon in the writing stage into a long action sequence to make a satisfying, wham-blam ending.