I've done scripted RPs before, except we (as in the RPers) are the ones who control our own characters. The GM controlled the environment and most of the NPCs, but never us. Though there is occasionally a thing called 'bunnying', which helps move things along; basically it's an NPC or another RP character pulling somebody along. XD It helps keep things from slowing down or dying because two people are RPing like this:
He walked to the door.
She followed behind.
He opened the door with his key.
Instead, the posts are written like:
He grabbed her hand and walked with her to the door, opening it with his key.
See? Though usually, yes, permission is asked to bunny. Other times it's downright necessary to just do it.