Next add the two diagonal backs, one at a time. After the dog understands the left and right diagonal back, mix in straight backs and overs, always casting sequentially (back to diagonal back, diagonal back to straight back, diagonal back to over). Once the dog has mastered these five casts, add the left and right come-in over and straight come-in (you must move your position on the straight come-in so you are behind the bumper).
Note: the following is a rough draft covering some aspects of transition
The first thing I do after completing the double-T is to teach the dog handling and casting wagon wheel. This is a drill with eight bumpers spread out like a clock. You first teach the dog to line each of the bumpers. The distance here is about an easy toss of a small white bumper away from the center point of the clock. Use white bumpers in short grass so the bumpers are easily visible to the dog. Work very hard to teach the dog to heel both clockwise and counterclockwise. Be very precise is staying exactly on your center pivot point. This will force you to make the dog heel with you, move with you, not you moving to the dog.
The premise is when a cast is given a dog will respond correctly after casting has become a
set of condition response (taught). Handling becomes a skill after much precise practice has developed a clear picture for how the dog is supposed to respond to any given cast.
This set of training begins with basic lining/handling followed by single T. Then it is on to swim-by. After that we are well into the process called transition. Pattern blinds are just a brief, next step in the process. The pattern blind focus is to simply "go" to a known position and quickly proceeds to a body of work revolving around Hillman’s Star Drill “combination”.
For example, in the following setups, the dog is lined and then handled to various positions. The dog knows where each target is, but will be asked to take many different casts determined by the trainer. Properly focused practice produces conditioned responses (handling) and the dog responds correctly to the stop and "ask" for "what's next" routine.
Depending on the dog’s skill set, somewhere in the above (it depends) each dog will begin cold blinds in the manner used by Danny Farmer (seamless).
Next teach casting wagon wheel. Same white bumpers and distance as lining wagon wheel. Start with three bumpers, the back and the two overs. This should be easy because the dog has just completed the double-T. The biggest change is that now you demand that the dog turn left on a left back and right on a right back. There should be no collar pressure on this drill. Either handle the dog or no him and recast to correct mistakes. If mistakes persist, mark the spot by tossing a bumper to the location of the cast he misses.
This means he is well force broke, collar conditioned and has spent a long time mastering the double-T. He should be forced from your side, forced en route to the back pile and casting to two sets of overs.
Concentrate on the five cast wagon wheel (back, diagonal backs, and overs). Once the dog has mastered the casting drill you are ready for your first cold blind.