Two players have different tasks while underhand passing. One passes the ball as high as possible, the other passes it as parallel to the court as possible.
After 10 consecutive passes players change their passing way. Passing quick is helpful when you want to accelerate action, in contrast when digging or passing from behind baseline ball should be played high so a setter could prepare and set the ball to lose blockers.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.