It’s not just for Tai Chi.
After having studied Tai Chi for a while, I felt a connection between the various moves of the form. I also found many of the biomechanical concepts that I had learned for power generation could be included in the kempo movements. This doesn’t mean that kempo is tai chi, and it doesn’t mean that you can do kempo slowly, and say that you ‘invented’ a tai chi form. Tai Chi has specific principles like creating a ground path, etc, that just don’t completely jive with kempo.
However, the idea of slow practice is a good one. ‘Muscle memory’ is the state where you can perform a motor skill without consciously guiding it. This happens regularly, and is the source of consistent good performance at the elite levels. The secret? Repetition. The other secret? Slow repetition. It’s easier to get a feel for a movement at a slow speed, as you can attend to all the micro-adjustments you make over the course of a technique when you go slow enough to pay attention. Thus, it takes fewer repetitions to achieve ‘muscle memory’ when you work slowly.
“But how will this make me be fast and get that snap?”, you ask. Tension is the enemy of speed. If you are performing a backfist, yet your bicep is tense, you will have a slow backfist. It is much like driving around town with your parking brake on. You get nowhere fast and can even do some damage. If you work your forms and techniques slowly, you can work on relaxing the antagonistic muscles permitting free and fast movement. Once you can perform the movement smoothly in a slow manner, speeding it up is easy.