To answer your question of why rushed art tends to be better, I think it's because you don't tend to have a lot of expectations about it. Also, you tend to use your feelings and guts in guiding your art more since you're not so focused on details. But when you're actually set to spend a lot of time on a piece, you tend to critique every single little thing you do, and so the outcome is never what you wanted. Anyway, that's my experience. That's why my drawing teacher taught us to actually start off very loosely and add details later, cause if you focus on the details from the beginning, you'll keep correcting yourself. Anyway, I love how you drew FlutterShy and Rainbow Dash. They looks really cute!