I had not heard of Sungha Jung prior to your post so looked him up on Google. He has a very solid foundation behind him thanks to his father and his own initiative to search out knowledge. So it would be my guess that Sungha Jung has a very solid understanding of the foundations of music - foundations being another way of describing theory.

For me, things made more sense once I began studying theory. It helped me understand why music is put together the way it is.

It makes no difference if you want to be a lead guitarist or rhythm or just make stuff up on the fly. Knowing the structure is important.

I understand you are a student and perhaps the cost of gaining full access to GT is not in the cards. However, there are many other ways to get the information thanks to the web. I would begin a study of music theory.

If you are as you say, you are accustomed to high levels of study. Music theory should be a cake walk.

Good luck