/ic/ - Artwork/Critique

I am reading keys to drawing. Look at this. The lines are messy, there are lots of restatements, there is barely any shading, the head lacks any features, the arm on the right is transparent, some lines don't even make sense, it looks like it can be drawn literally in 15 minutes. Yet, it still looks orders of magnitude better than anything I draw, even if I spend days on the drawing. How do I achieve this? What makes artists able to scribble for couple minutes and have a good looking result? How do I learn this power?