I agree with Tucson and others. I think almost every pitcher should have another position--not every girl will be another Cat. Also, there's the issue of both stamina and injury. DD had the shoulder thing and was out over a year. Today, she doesn't pitch more than 2 games a day, and I would prefer to see only 1.
Part of the stamina thing has to do with size. A big horse can be ridden longer than a small one can, if you run them the same speed. DD is only 5 nothin' but throws in the low 60's (see an early version of skills tape here, if interested)--
http://www.youtube.com/watch?v=dwqI1z9G3WQUnfortunately, that's a lot of stress on a smaller body, so it pays to be careful. Her team uses 3 good pitchers, all of whom can play other positions well, so a good rotation is no problem. On varsity, pitching 2-3 times a week is a vacation!