From what I've read, it seems to vary greatly depending on the ryu. With Tenshinsho Den Katori Shinto Ryu, for example, I get the distinct impression that they want to keep the entire school under the same banner. Within the past few years there have been authorized groups studying under sensei in the U.S. and Europe, but from what I've read all of these students are still expected to go back to the original source if they really want to practice the school. On the opposite extreme you have ryu that expect you to go off on your own. Mr. Amdur writes that it is a tradition in Araki Ryu to go off and start your own unique faction once you receive a teaching liscence, adapting the original teachings to the circumstances that you find yourself in when you set up shop.
David Sims
"Cuius testiculos habes, habeas cardia et cerebellum." - Terry Pratchet
My opinion is, in all likelihood, worth exactly what you are paying for it.