Most training regimes train multiple skills.
See this thread in the main forum
(381.1) which indicates that Outside Shooting, Jump Shots, One-on-One, Handling, and Inside Defense all improve driving ability.
I think the distribution is unknown. I'd guess one-on-one and handling might have a larger effect. For the shooting skills, the increase in driving might be related to being able to fake a drive which could move defenders off of you so you can get an easier shot.