Thanks for both of the replies.
Derek, in reponse to your suggested routine, I've been reading up on grip training on the gripboard, and it seems to me like most of the stronger guys dont go for high reps when trying to get to higher grippers.
I did some reading on the KTA program (supposedly the best way to move up a gripper number) and from what I gather its mostly singles. I imagine that training grip is like training anything else, and that reps 5 and below are best for strength, while high is more towards hypertrophy and endurance.
This is pretty much a long winded way of asking why you chose up to 20 reps for these exercises.
Also, I'm on the lookout for a sledge hammer, because I think my lack of wrist strength is the only thing keeping me from a one arm elbow lever.