Good question. I read once that the difference in release point between both sides of the plate is so small that it’s something that must be felt vs something that can be taught. It is, however, definitely something that can be practiced and refined through focused bullpens. I try to get a pitcher to aim every pitch for the exact same location and to remember how the delivery felt and what was the target they chose in order to hit it then try to repeat it or to make an adjustment and continue. Hitting spots is difficult and hard work. I try to make it fun.
With kids, I get a batting tee, a bucket of balls and a soda can. Place the tee at the height and position you want to develop, place the empty can atop the tee. Have the kid knock it down. They are all smiles when they hit the can. They knock it down and you keep setting it up in the same spot for the entire pen.