We have always seen Naruto using this technique - Taju Kage Bushin no Jutsu. I agree that Naruto's stamina is 5/5, but.. he uses the technique for an unbelievable number of times.
For example, let's say he has a chakra level of 100%, and he creates 3 clones, which means each clone will have 25% chakra of the original.
- If 3 clones get destroyed by an opponent, or
- Naruto undoes the jutsu
In both cases, Naruto learns the information the clones have gathered. Do they also return their chakra back to Naruto?
Ideally, they should return in case 2! However, I am not sure about case 1.
If they don't, then Naruto's chakra level should go down exponentially, as long as he creates new clones.
Now since Naruto has mastered Senjutsu (which of course has a time limit), he can create 2 clones in the battlefield itself with the help of natural energy. Also with Nine Tails chakra, he can create unlimited number of clones, because Tailed Beasts possess unlimited (compared to human limits) amount of chakra. But how about his battles prior to his Senjutsu or Nine-Tails form?