Start with the ball with one of the middle players who volleys the ball to the middle player they volley it back to the outside player who then volleys over the two middle players to the outside player on the opposite side as the other players are working the players that have just worked change places and repeat. This exercise is for players to be able to control the ball over differing distances. Again this can either be measured by time or number of good volleys.
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.