It does teach you the technique though. When you're kicking slowly, proper technique and balance are much more important, so when you kick more quickly, it's a better overall kick. No clue about the fast twitch slow twitch stuff, it all goes over my head.To increase fast twitch muscle fibers you either need to do fast explosive movements with light weight or heavier weighted slow movements.
Doing slow movement with less weight and more reps develops slow twitch muscle.