Set up as shown with 5 cones on the court, with one in the middle. The player starts at the centre cone and needs to run to each cone via the centre cone.
As a lot of movement in volleyball defence is lateral, which means players may perform a lot of shuffling during a game.
Running this way you develop agility, speed and orientation.
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.