Wrong Sluggers. The ones I had that did that were exceptional and had been trowing since they were 5YO They were at the extreme at that end of the scale. Both went on to college, no injuries.
The 16 YO I mentioned, dont remember seeing her plkaying at the 18U level at all.
Additional;' Both those young ladies had started pitching at 5YO and had worked their way up to that amount over those 5 years. I also felt that amount was excessive but the Dads said it was not, that was their normal workouts. One of the Dads had two older daughters that both went to college as pitchers.
Your 2 are the exception, unfortunately lots of coaches and parents hear such things and think that it it something everyone can do. Lots of 10u girls pitch entire tournaments and are out of the game by age 13