We don't call an offensive play # on each pitch. I'd say maybe 1/3 of the pitches we call something. Of those, many are simply hit away. We've found that when you don't call something on every pitch the defense seems to react and assume you are stealing or bunting when you do call something.
I don't use the wristbands as much as I should, but I have dummy signals for this. Our cards are simple and only go up to 3. The girls are told if I flash a 4 or a 5, it's a nothing call.
The problem is I get "wait, what's that?" looks when I use it, so....