Okay, I have spent more time than I care to admit reading this thread and have only gotten to page 12, so I'm jumping to the last page now. Hopefully I didn't miss anything (judging from all the previous comments I'm guessing not, since this discussion has shown to be essentially circular).
When I first read what Cherrie originally said, my immediate thought was that my horse would launch himself into a bucking fit if I did that. But then the more I thought about it, I DO do that. It's as simple as this example:
I ask my horse for the left lead canter. He responds by not cantering correctly (the canter depart is included in the correctly part). I bring him back to a walk and give him one good whack with my dressage whip (disclaimer: more horse has never had welts, lacerations, etc from me "beating" him). The whack is to say HELLO, did you hear me?! Its almost like a wake up call to get their full, undivided attention. However, I am not giving him the cue to canter during this whack (I don't know if I differ in what others do in this regard), it is simply a whack. Hello, wake up, pay attention. I then ask for the canter depart and he ALWAYS gives it (or whatever other transition I'm asking for) immediately. I just have to shift my weight to the outside and we are cantering.
I ask for canter. Correct canter not given. Stop asking and give wake up call to horse. Ask again. Correct canter given. Praise - good boy!
Maybe I am entirely missing the point and "not getting it", but this is what I do and it works for my horse as well as other horses I have ridden. And isn't that the bottom line, essentially? Does it work for you or doesn't it?
Hope this helps somewhat!