I’ve never been a huge fan of blocking against hitters on boxes. My big problem with it are that the way these drills are often run is that they very often eliminate the read/react element of things and/or operate at a tempo that isn’t very game-like. This version is perhaps the best I’ve seen, though. In having a live setter working off a pass, the blockers are forced to try to read and react. Plus, the tempo of the attacks is pretty much game speed.
Now, that said, there is still a big short-coming. It’s one that is tough to get around with hitters on boxes. I’m talking about the lack of a hitter read for the blockers. They basically know exactly where the hitter will attack the ball, so there is no reading of that. In other words, it trains the blockers to simply go to a spot, which is a problem I see all the time.
That being the case, as much as I think this is a better version of blockers vs. hitters on boxes than most, I would still be inclined to only use it infrequently to work on very specific things (penetration, communication, movement, etc.).