I was wondering if the uchiha clan learn to cast genjutsu onto themself to create a illusional world that they can create stimulated battles of their oponent/ninja they observe with their sharingan .They will learn how to counter their justu better or learn jutsu from them base on hand sign pattern.They will not the physical aspect of training since everything they saw can be copy or practise in the genjutsu world they created.
Picture Itachi copy all the akatsuki moves /technique with his sharingan and then cast a genjutsu onto himself ,then stimulated a illusion vision of them which they can be use train him their jutsu or improve Itachi skill level.
Picture Itachi copy all the akatsuki moves /technique with his sharingan and then cast a genjutsu onto himself ,then stimulated a illusion vision of them which they can be use train him their jutsu or improve Itachi skill level.