Kurama has never given Naruto battle assistance outside of the typical chakra boost. I know that kurama sometimes goes on rampages but in most battles Naruto is conscious of his actions. Thus it's up to Naruto to use efficiently use kuramas chakra otherwise it would be pointless. Think about it like this, just because Kurama had millions of more chakra than Madara did does that mean Kurama would win the fight? No. Madara placed Kurama in a genjutsu rather quickly. Brawn over brain is essentially what I'm saying. Naruto still has to know how to use the chakra. Nowadays he can just shoot a bijuu dama and murk everyone on the battlefield but in the past he had to survive against opponents who could easily exploit his flaws and kill him.
Kurama wasn't Naruto's right hand man until the war arc started. Naruto had to come up with the strategies and techniques to win the fight.
[video=youtube;FrVUl9-C8l8]https://www.youtube.com/watch?v=FrVUl9-C8l8[/video]