Why on earth would you need to wax the string after a few shots? Heat is not you bows friend so don't leave it in a closed car on a hot summer day, this is hard on the string.
I'm lucky to wax the string on my bow once a month during the hunting season. I inspect the string and if it looks dry I wax it, otherwise, I don't see a reason to continually wax it. I would imagine that once a week would probably be quite enough, although, I may be wrong.
God, Family, Guns, in that order.