The Problem with Knowing it All. . .
In anything, especially training, we can never really know it all. Even true Masters will tell you they have a lot to learn still. Champions stay champions because they continue to improve. The champions that do not continue to improve do not stay on top very long.
When we think we know it all (which happens to the best of us) it is impossible to learn because in the back of our mind, we think we already know what is being presented. Our mind is closed because, "we already know that" or, "I know better." Unfortunately, most of us have run into a few who knew it all. They're usually the ones that watched everyone who didn't "know it all" fly right by.
Research your own experiences. . . have you ever thought you knew it all, only to find out later the hard way you did not? This is martial arts as a mirror to examine yourself. One of the greatest things we can gain from training is humility.
The fastest way to learn is to have the mindset of a student. At the most basic level, the student mindset assumes we do not know everything and that there is always something new to learn.
Be a student.