Kim Jung Gi is the master of drawing and illustration. People who are interested in illustration or animation probably already know him. But I just recently found his videos while watching just a bunch of random videos on Youtube.
Most of his videos are 30 minutes to an hour long. You might think they would thus be quite boring to watch, but they’re not, because he never rests — he just keeps on drawing for an hour without thinking about what he’s going to draw.