Master Shot Usage during a scene

I'm using Final Cut Pro HD and I have an editing question for anyone out there. I'm currently working on a movie and I set up a scene (three actors) with a master shot and then I moved in for some coverage on the scene. During the conversation I mixed in one or two master shots so the scene would not drag on. Another editor told me that once you move into a scene you can't go to the master again, unless you are leaving that scene. I was under the impression that as long as the scene works, doesn't appear to be jumpy and doesn't take the audience out of the scene, then you should be able to use master shots within a scene. Am I wrong?