This is a great way of getting your players to understand the zonal area they are expected to be in, whether defending or returning to their position after digging up the ball in preparation for the opposition's return.
For advanced players there might be also 3-meters attack introduced from Zone 1.
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.