I saw your confession on Artist's Confessions on Tumblr and I wanted to tell you personally that there is no such thing as complete art.
People, from the dawn of time, have always felt that their works need to be tweaked, detailed, perfected, even if there is nothing more to improve and the work is finished. There can be instances in which an art work needs improvement, but as long as you feel it is done, there is no need to push yourself beyond that. I mean, I know I haven't reached my full potential - I'm kinna too lazy to reach it - but don't force yourself in doing things just because you see other people do it.
And here you can improvise. For an artwork to appear more finished and refined, try adding different types of shades or textures or shines and highlights, anything that can make you say: "I've done enough on this part of the drawing. It looks good. I needn't tweak it more!"
The purpose of looking back on what you've already drawn recently - and posted it - is to look at the piece and realize that: "I have made a mistake/ this drawing seems a bit unfinished. Next time I will try to improve/ refine the drawing more. " Coming back to a drawing to improve it is just walking in place.
Your aspirations shouldn't be towards what everyone does. Heck, if I were to do that, I would have cracked up a long time ago because I can't paint and most of the deviations I have as favourites are from digital painters. I've tried painting but I failed miserably. I realize I am not cut from the same cloth as they are, that's why I try to improve my own technique in being a mock-ery painting or an imitation of what others do.
I am giving you this advice from a different perspective, but I realize what you are striving for and it is high hopes. Instead of high hopes, why not take baby steps. You'll end up where you wish through them, no worries!