Re: Instructors of low rank
While there may well be folks promoted to 3rd or 4th dan after just a few years, I don't think it's common. I've trained for 20 years now, and in that time I've never met anybody who was promoted like that. The fasted time to shodan I've ever seen is about 3.5 years. He was in his early 20s, trained 5-6 days a week, went to every seminar and camp he could, AND had natural talent. There was no doubt that he deserved the rank.
I should say that all my training has been in various dojos in the United States (both USAF and ASU) - other groups may regard ranks differently.