Beth,
I'm glad you started this thread. If you study with an artist whose work you like (and that should always be the case!), I think it's waste of time and energy not to at least try out a new palette (or a new technique, or a new anything).
By "try out" I really think a new palette should be used for a minimum of about three months in order to really explore which, if any, aspects will work for you. I find that I need to get into a new rhythm and mindset when I work with a new or amended palette. I don't make changes often, but I'll change in a heartbeat when I can see something works better, more reliably, or is just plain easier.
Julie, I was surprised to see how much is written here already on
Stephen Quiller