Two players stand on each side of the court, with two balls between the four players. These two balls should be with players on the same side. The two players with balls set to the players opposite them, and switch places with the other player who set the ball. The players opposite meanwhile, set the ball back but stay where they are.
This drill improves setting accruary and the need to shuffle and bypass a teammate to set the ball, as this is something that will happen often during a match.
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.