What’s the one, most important thing, that you should dedicate yourself to if you want to understand Jiu-Jitsu in-depth?

Sure, there’s a ton of things that will need your attention… But the most important of them is utilizing the trial & error method.
Why? John Danaher explained in an interview for BJJEE:

I was known for spending large amounts of time on the mats.

I taught two to three big group classes per day and was booked every hour between them for private classes.
I liked this because I was a very late starter in Jiu Jitsu – starting at twenty eight years old – so I felt that I needed to accrue many hours of mat time quickly, to match the hours people who started much earlier in life had already amassed.

Much of it was simply teaching people how to perform better in Jiu Jitsu, but because Jiu Jitsu is a very hands on sport and I personally drilled and sparred with everyone of my clients every time I taught, I got countless opportunities to identify problems in my game and the game in general, and would always try to improve the solutions I had been taught.

In other words, he always had new things to try and improve upon.
Which is exactly what earned him such a deep understanding of Jiu-Jitsu that he has today:

The central feature of my method over the years has always been a TRIAL AND ERROR method, where every day presented numerous opportunities to try new theories and concepts and test the results.

At the end of every day (I worked as a nightclub bouncer in the evenings) I would reflect upon the main themes/lessons I had learned and begin the process again the next day.

 

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