Naruto IS to an extent a hard worker, but no more then Sasuke at least.

Neji and Lee both surpass him in hard work as Naruto even had hints on how to do the rasengen and a teacher - Neji learnt the kaiten all by HIMSELF.
He also learnt how to see the chakra points in bodies by himself, Lee worked twice as hard as Neji but Neji worked twice as hard as Naruto.

you cant say just because they're genius's means they dont work.
Sasuke constantly trains to be stronger then his brother, when hes not on a mission hes training. The only nins you can say dont train as Shino and Gaara basically.

the point is that Naruto isnt as much of a hard worker as people make him out to be, he only works hard when theres a deadline, otherwise he slacks off.
in both situations he was working against a deadline - Rasengen in a week and the few days training before Zabuza made his reappearance, oh and also the month before the chuunin exams.
The ONLY time Naruto starts training is when theres a deadline to be met.