How many characters should there be in a play?
Oleanna has two players - professor and student. The play is very cat and mouse, and any additional players would distract from what's going on.
The Road to Nirvana has the two filmmakers, a superfluous wife, and Madonna. I think there's another character in there somewhere, but I can't remember who he was exactly. This play is also very cat and mouse. If you ask me, it has three too many characters.
The point is, if you're going to take up an actor's time (and in L.A., that's a big deal) at least give them something worth doing! Forgettable, thankless roles wind up being played by members of the crew, when the actors originally cast get bored and go off chasing national commercials and soap opera auditions. NO role should be forgettable and thankless. That old adadge "there are no small roles, only small actors" is complete nonsense, and we all know it. Some roles just absolutely suck, and are the result of lazy playwriting.
Look, if the character exists only to deliver a tray of cookies, cut him! Or give him a poignant and touching monologue! But don't expect an actor to jump through the hoops of the audition process and show up for every rehearsal just to perform Larry the Butler (for free.)
More about this later ...