While it is entirely up to you how you want to write (which is the beauty of screenwriting) I would argue that where you’re using an em dash, you could be using a comma to get the same effect without cluttering the page too much.
He runs to the cabinet, pulls out a bottle of booze.
Does pretty much the same thing.
I like to use em dashes to get us into a new slug line without burdening the reader with clunky slug line etiquette.
He grabs his bag and runs into —
INT. HOUSE — DAY
Where Elanore waits for him, impatient.
Saving em dashes for specific moments also makes its use more effective because it’s different and calls attention to it.
But solid article, buddy! Keep writing both medium and screenplays. If you ever want feedback on a script email me: firstname.lastname@example.org.