The always interesting young woman who blogs as The Intern talks about that phenomenon when it comes to the YA manuscripts she sees - and how often a new author will try to fix things, not by growing something organically from the story, but by forcefully adding some new, clashing elements.
She says, “So many YA manuscripts start out fun, crazy, and wonderful, then enter this weird spiral where the author doesn't know how to resolve all the zany hi-jinks and starts freaking out: "OKOKOKOK....moon people! That'll be hilarious! Aaaaaaand....I'll say that all this time, the antagonist was secretly a hummingbird! That'll solve everything!" Instead of using elements that already belong to the world of the story, they start looking for an extrinsic solution, which, even if it kinda works, is never as emotionally or intellectually satisfying as a solution that comes from deep within the story.”
Read the rest of her advice here.