If she had excellent control of her drop, she would throw it two or three times to each batter, changing the location and speed each time. Sometimes she would throw it back-to-back-to-back.
My DD is at U14 and the older one playing in college now. I've had the opportunity to watch the older one go through the recruiting process and see pitchers pitch through U14/U16/U18 and now some college which is helpful. Just as this board is. The younger one is U14. I'll have her throw her drop to the same spot 3 times if the batter looks perplexed and won't take the bat off the shoulder (which happens sometimes). At this level, my expereince is most righties can't hit an outside drop or drop curve well and I'll make them swing at it before I move location. Often times the swing is a ground ball to second.