Something that is one of the hardest thing I learned is handling critiques and criticisms well, I'm not saying all, but I think it depends on the artist's ability to accept critiques and handle criticisms well (take note that the two are entirely different as critiques refers to pointing out the areas of improvement and telling the other person how to improve it , while critics only points out your mistakes and what they don't like)
Critiques and Criticisms are unavoidable but the ability to handle both, actually takes time and solely depend on the person/artist itself.
Most of the artists I met before used to skip fundamentals and basics and just jump on with their art and even has the overconfidence to insist to other people that --" this is just my style so I don't need your critiques" -- which is entirely the reason why their art never grow. I know Art is all about having fun, but it always depend what are you making your art for ( for example, you wanted to become a professional, of course you have to improve to become professional) having Confidence is a good thing to have once in a while since you will need guts to put yourself out there but overconfidence is a different story.
I'm not saying that learning fundamentals is the only way as we all have different learning styles when it comes to art but having knowledge on the basic things, will always help an artist in the long run.
Also time plays a role, the more time you dedicate to improve your art, the faster you will improve and we artists have different paces.
But like I said earlier, in the end it will still depend on the person if he wants to improve or not.
