KRD is a nice flexible drill for Transition, as well as for maintenance. But if you're looking to move forward, you'll probably be better off just showing your pup some simplified variations of diversion marks with standard concepts at relatively short distances, and keep proximity wider at first. As he shows he's getting the idea, add length and tighten things up a bit at a time. Read the dog, and advance him as he shows readiness.
I love drills. But they have a limited scope of usefulness in general. They're great for establishing skill. But you need to understand when it's time to move on to real work...real set ups. You may not be there yet. But only you can know that.
Evan