How often should you be allowed to ring a girl in one day?

I know it is frustrating to have to wait in a queue, while the same callers seem to monopolise the lines hour upon hour, but I can't see any of the channels limiting the number of calls each one can make, as - by definition - that will reduce the total number by a considerable percentage!! As it is a premium number though, so maybe no caller should be charged until connection to the chosen girl on screen?? I know there is a disclaimer to the affect that there is no guarantee of getting through to the actual presenter herself, but this could apply to being connected to one of the 'phone bank' operators also - if the callers want to talk to an alternative girl!!