I've read somewhere that in the wild, coral banded shrimps occupy cleaning stations which roughly cover a 55gal area per station. I suppose this would translate to having only 1 shrimp in your 10gal tank.
My coral banded (lone shrimp) has been in my tank (55gal) for the last 9 months and has grown almost double in size since the first day I got him. He eats everything I throw into the tank
Hope the info helped a bit.