This question is very interesting. Kakashi and Jiraiya are both Naruto's teachers, but Kakashi seems to have nothing to teach Naruto, just to help Naruto master the practice of spiral pills! Jiraiya, on the other hand, personally taught Naruto to use spiral pills. Why do Kakashi and Jiraiya know how to practice Ninjutsu for hundreds of times, and why did they only teach Naruto Spiral Pills?
One reason that can't be ignored is that Naruto can't learn Ninjutsu, which is too complicated, because his grades in Ninja School are very poor since childhood. However, this can't be said that Naruto is stupid. Naruto is a fighting genius, and he can always win with his wits. How many talented masters are defeated by Naruto's calculation, even God is no exception.
Why did Kakashi not teach Naruto Ninjutsu? Kakashi itself is a thunder attribute, and his own development of Thousand Birds, Naruto also wants to learn this trick, but Naruto is a wind attribute, and he has never learned this trick. Kakashi only taught Sasuke this trick, and Naruto complained that Kakashi was eccentric. Kakashi basically didn't teach Naruto Ninjutsu, but more taught Naruto how to behave.
Jiraiya knew that Kakashi was unable to train Naruto well, so he personally taught Naruto Ninjutsu. Although Jiraiya mastered hundreds of kinds of Ninjutsu, he finally taught the Ninjutsu pill. Why?
First of all, Jiraiya knows Naruto's life experience and Kyubi no Youko Fox. He also knows that Naruto is a wind, so it's appropriate to teach spiral pills. Spiral pills, a endurance skill, was developed by his father, so it's natural to teach them to Naruto. Besides, although Jiraiya is a womanizer, he is still very responsible in teaching his disciples, and he must teach Naruto the ninja skills that are most suitable for him to practice.
Spiral Pills are still very powerful. Not many people have mastered this trick, only four generations of Huoying, Jiraiya and Kakashi can also know a little. I have to say, the spiral pill is really tailor-made for Naruto, and a ball has been rubbed for a lifetime.
Therefore, no matter how many endurance techniques are available, they can't compare with those suitable for self-cultivation. Only the endurance techniques that are most suitable for oneself can exert the greatest power of spiral pills!