We started using the wristband coach because our kids saw it at a UT/Vandy game when we were 13U. Our team got to talk to the UT players and they were telling them about it. They asked if we could try it. So, I made the grid like this:
1 2 3 4 5
1 FB in FB away CB CU FB in
2 FB away CB CU FB in FB away
3 CB CU FB in FB away CB
4 CU FB in FB away CB CU
5 FB in FB away CB CU FB in
To be honest, we used it only when we heard other teams calling out our signals. Our catchers called 90% of their own pitches so we used it as a decoy as well. I thought it was wise to expose them to yet another way to play the game.
NOW...the interesting part of this is that we started using it on offense as well. Mostly, just baserunners and which pitches to steal on.
I know U of Texas uses it on offense as do a few PAC-10 and ACC teams. Most of the ACC, SEC and PAC-10 schools use it on defense.