(C)oach is a refering and introduct the balls to the winning side.
Players can only play one touch and then get out of the court to let their teammate take their turn to play.
First team to 15 pts win and the loosing team do physic exercice while the winning team picks up the balls.
As I considere this exercice as warm up, I include that the 3 meters area is off court.
If your players are very good at it (and to improve their control skills) you can make this exercice with open full court.
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.