With all this practice, it's got to be the mechanics that are being taught. Are you teaching them to swing down and hit the top of the ball ??
What are TCB balls?
Why do alot of coaches do this?The HC of dd's TB team likes this speed drill,I hate it the first time he tried it with my dd she was mad at him.She told him to slow down,because she wanted to get reset,he listened to her but,did it with the other girls.Another thing about machine pitch, toss drills or TCB balls. A lot of Coaches seem to think it is a race to get as many swings in as possible. Keep a good pace but do not rush the player. Like Amy said have a home plate, ideally a batter’s box too. Do not rush the batter; let them get in a good position to have a good swing. It is not a race.