If I read it correctly, the rules there confirm what Juicepats said, but don't mention that other claim that repeating a training several times will make it slower regardless of all other factors. I hope I got this right now.
i think it is a logical thing that training something several times will make the training slower, becausethe proportion betwenn trained skills and coneected skills will get worser after each training.
But i startet training with player like JS inept and Jump Range respectable, so i make sense to train a lot of Jumpshot without training JR even if the "bonus" is reducing every time i train Jumpshot Jumprange training works still with less efficiency.