I've written 9 screenplays (one of which got made into a movie, Solitary) and I'm currently working on my first book. (I'm a programmer by trade. Writing is a hobby.)
When I first start writing dialog, I had a hard time. My dialog was what I call ping-pong dialog, i.e. dialog that went back and forth too much. I found that I could compress 4 dialog lines into 1 or 2.
In the process of learning how to write dialog, I spent a lot of time reading it aloud and I still read everything I write out loud (including my book). And when something doesn't work, my first step is to REMOVE IT.
If nothing is lost then I've fixed the problem (BTW, I find this approach helpful in programming as well. When I'm deleting code, I'm usually doing the right thing.) And most of the time this works. But when it's a necessary piece of information, then I apply another rule of mine, Smallest change, largest impact.
The idea is to make the smallest change, in this case add back the fewest words necessary to convey the previously deleted idea.
Writing screenplays is an exercise in parsimony. Try reading screenplays to see how the professionals say more with less words.