Did not read whole thread so forgive me if this has been mentioned. 10U pitchers should throw bullpen at practice. Preferably to a AC or parent. Those stand up mannequin that mimic a batter are great for teach pitchers to throw inside. Hitting should be done at multi be stations including tee work, front toss and pitching machine. Live at 10u doesn't work well. At 14U and up live can be done with rotating pitchers as Cannonball mentioned. Each batter gets 2 ABs and starts with 1- 1 count. First AB pitcher throws fastballs only. Hitters that can't time up and hit FB when they know it's coming should play soccer.. This is why pitching machine hitting is very important, IMO. If a hitter can't hit off a machine they 'probably' can't hit. Second AB catcher calls the pitches and tries to strikeout batter. Competition.
This is why people call the parents of pitchers "crazy". No F'n way would I have my daughter at the 14u level and up, go to a practice and throw only fastballs to hitters, that is a waste of time for any 14u pitcher and above, as well as dangerous. Might as well just stay at home and do our own pitching practice.