How do you level up final form faster in Kingdom Hearts 2

Hi, I did this in about half an hour. Go to the world that never was, twilight's view. Go past the area where you fight xigbar then turn to final form. Fight heartless until you have about 2 drive bars left. Quickly head back to twilight's view and go to the world map, still in final form. Land in the same place again. You will have max drive. Keep repeating!