We're so blessed in 30A to have Brother Emile Bussemey for a district instructor. His time at our lodge instructing is something several of us wouldn't miss for the world. Patient, takes the time to teach the whys and whatfors, and is a very intelligent man (retired geophysicist) who has been around masonry a long time.
He is at Holland #1 mostly, but he comes to our lodge sometimes and we go to Holland to see him too. I've heard stories here and there where some folks have butted heads with their DI, but if you're blessed to have a good one like ours I can highly recommend it. Its one of my favorite things to do, especially degree practice or round robin Q&A's. It feels like a team sport sorta.
That, and the relationship built when learning the initial Q&As between the candidate and his instructor is why I figure the codebook ought to be used conservatively. The mouth to ear business is just awesome for building relationships between brothers.