Okay so, transitioning from a Leaf Uchiha, easy as hell to spam the waterfall mission and train, to a Sound Kaguya, this is very difficult. Anyone in leaf can easily just spam waterfall over and over until they cap, I mean hell I used to do that. I recommend that either experience is a little higher for C and D ranks for Sound and, possibly Sand, depending on difficulty to train there, or that there be individual village missions. For example, something Sound could do just as easily as Leaf can spam the waterfall mission, perhaps something involving the nearby waters. I find it harder to spam the waterfall in sound, due to the waterfall being a greater distance away.