Our protocols have been implemented the way you describe for years. It seems to work good, but you can't be a "protocol compliance" robot in that environment.
That's a good thing!
I think that many progressive EMS services are moving towards guidelines. It seems like with guidelines there are less pages than with protocols. If you dont have to have a protocol to cover every conceivable situation then you wont need as many pages :) I like to think that it creates less stress for the providers too, they dont have to try and memorize the whole cookbook... Besides, I think it promotes critical thinking and a REAL knowledge of why and how you are doing what you're doing and not just step 1 - step 2 - step 3.