How does teaching improve a persons Jiu-Jitsu, and should teaching be a requirement for promotion to black belt? 

I believe teaching, especially the fundamentals, has greatly enhanced my Jiu-Jitsu. Teaching forces me not only to present the technique, but to demonstrate it in a way that I would want to learn it myself. It makes me focus on the subtleties, the simplicity, and the key components that make a technique work. 

By teaching and repeating those techniques over and over, they become ingrained. The technique stops being something I memorized and becomes something I truly understand-something that becomes part of me. 

That said, I don’t believe teaching is for everyone, nor do I think it should be a requirement for earning a black belt. There are many outstanding practitioners who may not have the desire or aptitude to teach. However, I do believe that spending some time teaching can only help a persons development and deepen their understanding of Jiu-Jitsu.