Honestly all-region is not something you can effectively do in a classroom setting. I was previously an assistant at a large school in DFW (a 6A powerhouse as you say). We had many kids make all-region every year, but they all learned the music in their private lessons. Now I'm at a not-so-big school with hardly any lesson program, and hardly any kids make region. I've tried working it in class, but with so many different etudes to learn, unless you have several assistants who can pull sections, it's not going to be effective.