Board Thread:Theories and Speculation/@comment-25132842-20180415030219/@comment-25132842-20180415153700

There are about 50 named Jonin in the series. A number of them, namely Jiraiya, and Neji died. Some of them never became Team Commanders, namely Hiashi, Tsunade, Sakura and a number of other Jonin. That might leave about 30 Jonin available (if we're being generous). If we assume that most Academy Students in a class of 30 (say an average of 25) graduate every year and some years all of them graduate. This doesn't look promising for the number of Jonin available.

However, there must be unmentioned Jonin if they're able to keep this up, or some Jonin take another team after their first team. Kakashi's generation didn't have a good record of repeating. Kakashi just never took another team, Jiraiya and Asuma died, Guy was crippled, Kurenai had a child and retired, Sasuke has the skill of a Kage but technically never passed the Chunin Exam so is a Genin, Naruto also has the skill of a Kage and became the Hokage, but is still a Genin.

I get the feeling that Naruto's generation is atypical of Genin and Kakashi's generation is atypical of Jonin Commanders.