Players work in pairs with a ball between them, starting in a squat position. They pass the ball high, jump, and set it to their teammate who repeats this.
Jumping works the leg muscles and this drill helps players learn to jump at the right moment to reach the ball at the highest spot.
For professionals, when they jump they could spin in the air so they would set the ball backwards.
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.