In pairs the players stand on either side of the court facing each other (note this drill requires at least two sets of pairs - four players) Player 1 has the ball facing his/her partner. The player with the ball then spikes the ball off the ground to the other side where their partners catches it. The players on the same side of the court then shuffle sideways to change positions with each other. Player 2 then repeats what player 1 has just performed.
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.