HOLY COW!!!How many keyboards has he mashed now? Anyways, that's just insane. Although, I think he uses a mechanical keyboard, just to make the clicks extra loud I can't do that without really trying and ultimately end up getting cramps in my arm
Have you tried sticking to the scenarios at first, as opposed to a Full Custom game? It depends on what modes in official games you want to train for. Think of the joystick in a Pac-Man machine: there's a diamond-shaped restrictor plate in the joystick assembly to make you press straight, not diagonal. Tetris the Grand Master 2 and 3 machines have similar joysticks. 8-way: allow shift sideways and drop to be active at once 4-way: do not allow this Lockjaw calls this setting "Allow diagonal motion".
Keep playing, with practice you'll come to subconsciously learn the colours of the pieces, so that all you need to do to see the next piece is note the colour out of the corner of your eye.