Players stand in pairs on each side of the court. The player at the front of the pair attempts to jump and set the ball to the player at the back of the pair opposite them before moving aside. This player then sets the ball to the players at the front of the pair opposite, who does the same. The drill now begins again.
The drill is important for teaching players how to change the power of the pass, particularly when receiving passes of different speeds and heights.
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.