Players approach and jump and imitate a spike by holding the non-hitting hand up and hitting it as it it were a ball.
This time players are expected to execute full spiking motion in short time with no floor contact.
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.