I've been struggling with impostor syndrome forever, and I know exactly where it comes from. I've always drawn "my way" without actually focusing on what most people would call "formal" technique. It may be a plus, but i'm convinced it's acting in my detriment. My professional work so far, satisfying as it has been demands a very specific language, the codes are almost baked into the genre. This, I think, has made me comfortable, and makes me rely on the shorthand and not push myself technically.
This year I'll address this, through formal exercise, within a formal framework. Less "finished" pieces or blorpy divertimentos and more practice pieces.
Gods help me.