RoccondilRinon said:
1. What's wrong with having a four-act structure?
2. Acts are subdivided into scenes. I've never yet seen a film where an act break comes in the middle of a scene. Surely Screenwriting for Dummies 101 taught you that much?
That's a really dumb answer, mate. You've never yet seen a film where an act break comes in the middle of a scene? Possibly because you don't see act breaks. An act break is a transitional point. It is the scene itself within which the change comes. Ergo, the transition to Act III in Jedi comes within "Luke and Leia" when Luke accepts that he has to face Vader. It's about the meaning, not the technicality of a scene break.
Clearly you're the one who's never read up on how to write a script, otherwise your answer wouldn't have been so stupid.
Oh, and what's wrong with a four-act structure? Well, that depends on the medium you're writing for, and the story you're intending to tell. There are very few screenwriters who vary much from the industry norms, and there are very, very well established reasons for the three-act structure being what it is.