…for reasons that today seem inexplicable.
Yesterday I saw a blocker warming up but jumping landing on one leg, stepping in the opposite direction, jumping landing on the opposite leg, etc etc. It reminded me of my days as a young player when we were being taught blocking footwork. This was before specialisation so we were all doing all the footwork from each position. The most basic drill was to start from the middle, jump and then move outside. The idea behind it was to practice moving after having (incorrectly) jumped with the first tempo. Until very recently I would see this drill being done by professional players. In the most extreme version, we would practice (incorrectly) jumping with the first tempo and then landing on the opposite foot to the direction we wanted to move to reduce the time we needed to get to the outside (more or less as I saw yesterday). The idea behind it was that landing on one foot saved time in initiating the movement.
Inexplicably, I don’t remember a single instance of a coach teaching us a method to not incorrectly jump with the first tempo. Or even mentioning it as a possibility.