Okay, what I'm about to say will probably cause a ton of 'lmao pyw' replies, so I'll say this upfront: I love Kim Jung Gi's work, I think he's a fantastic artist, and I am definitely nowhere near his level. I've been studying his work for awhile and I have some pills to give:
I don't think Kim Jung Gi is as godlike as everybody says he is. He is absolutely incredible at two things: extreme perspectives and picture composition. The first is very learnable, the latter is what makes him so unique. NOT his 'infinite visual library'.
I have a few of Kim's sketchbooks. They're great. But, it is very, very clear that he reuses a set few prop pieces constantly.
The same animals usually show up, always pigs, bears, horses, and cat-like creatures (and cats all have very similar facial features). I have never seen anything deviating from this group.
The same guns always show up. Almost always a revolver or an M4/FN SCAR.
His mechanical drawings are usually good, but nothing astounding. The only incredible ones I've seen are of engine blocks, and, again, they are repeated across any drawing that features them. And with vehicles, it's ALWAYS the same helicopter/motorcycle.
The anatomy/faces, I'll give it to him. He has one of the least-bad conditions of same-facing I've ever seen in artists, and I have no clue how he's accomplished that.
You combine all these together with some genius-level composition planning, and it starts looking like you have an extremely vast reservoir of images in your head, when really you're pulling from a few select places.
Does this diminish his abilities at all? Of course not, memorizing even these limited examples to the point of being able to recreate them flawlessly in any angle is something that would take years of study. Past that, his ability to combine them together seamlessly makes him a master. But to the anons saying that he is capable of creating anything and everything, his years of past work says otherwise.