Sage mode controls the amount of chakra, not the shape or movement or element.
Agreed, but even perfecting that balance has it's benefits as it is one aspect of chakra control that Naruto can then apply to other chakra related activity. Also I would like to add that the natural chakra concentration is internal which is something quite different than trying to manipulate that chakra outside your body in your hands. With that said, I still believe that Naruto is very much capable of creating double rasengans without the use of a clone. He only needs the additional clones for the extra concentration the fuutonrasenshuriken requires due to the addition of the wind element.
Originally Posted by kuroihikari
A bridge towards peace; the will of fire still endures!
Rokudaime Hokage, Rokudaime Rikudou Sennin Uzumaki Naruto
Master of Bludging
It's true that by studying the Hermit Art of Senjutsu, Naruto's ability to control chakra has greatly improved, to the point where he could create 2 rasengen without clones. However, don't forget that in Sage mode, Naruto is still required to concentrate on balancing his spirital, physical and natural energy whiles trying to create the FRS. He might be able to create a FRS without being in sage mode, but he would need to concentrate 100% leaving him clueless on what his opponent is doing. By using 2 clones, one can concentrate on the opponent, while gathering more natural energy, the other 2 can concentrate on the FRS and timing.
Naruto still uses two clones for FRS because he needs to. He can't do it any other way. He tried making the FRS with one clone. The Results: Impossible to do. So it really has nothing to do with Naruto watching his enemy or whether he has great chakra control or not.
Pretty much what afro said I think it might be impossible to do it with one body. So Naruto breaks down the complexity that makes it impossible with one body with 3 and makes it possible.
Originally Posted by afro thunda
Even the 4th couldnt do it because it is impossible to "look 2 diffirent directions at the same time" with one body as they described it in the manga.