While I can see knowing the break speed for training, not sure how knowing the speed the cueball is traveling would work for any other shots. I mean you either get to where you need to be, or you don't, the speed of the ball does not matter. You either have the stroke to go full table, or you don't, knowing your cueball is traveling 10mph or 12 does not matter there, especially since the tables speeds vary quite a bit. For the break it's a bit of a different story since the cueball does not travel around the table, rather it sends the force into the stack, so it's hard to measure speed there. For an actual shot that goes around the table, you just need to measure how far it travels and how accurately not the speed.