I'm not a huge fan of having blockers working against hitters on boxes for multiple reasons, but this version is better than most I've seen.
This is a good small-sided game-play exercise that gets every player lots of touches and works especially on transition hitting.
Here's something you can do to help work on your hitters becoming better at attacking the block rather than just trying to hit around it.
This drill allows passers to work on receiving hard serves, and servers on serving them, but without lots of missed serves leaving passers standing around.
This pepper variation introduces playing the ball over the net, which increases the game-like element and movement and puts added pressure on ball-handling.
The second chance idea can be a very useful developmental idea in volleyball training, both in games and in drills.
This pepper variation expands on the over-the-net version to allow for more players to be included, potentially allowing for increased complexity.