I do not really look at art as a skill that you have to work your butt off. I see it as a talent in which you have fun doing not the care of the world whose around you. The key point in drawing in general is to have fun then you will see improvement in the future. For some reason I think in art no one would reach there limit unless there old as hell or their hands got broken or chopped off. You basicly improve over and over it's endless of changes as you observe your mistakes and how you change your interest. That is the way I see art just constantly improving but at the same time have fun. Word of advise if you know you like your pictures that is all that matters. I learned that as my experience growing up and now my journey in ART ONLY HAS JUST BEGUN.