Sometimes it shocks me just how much information is available on the web. For example I was doing a tiny amount of research about Dave Sim and way his comic Cerebus changed markedly over its 300-issue run (so much that I'd claim it's a stretch to say it's actually the same story or even the same type of story). And I came across this page on TV Trope about creator breakdown. If you read all that and follow all the links you have months of reading on your hands, I'll bet.
Related (because Dave Sim did this to an astonishing degree in later issues) is Author Tract. It's when an author starts preaching instead of entertaining. At the Writers Of The Future workshop, Tim Powers recommended us to not aim to put out beliefs on the page. Instead just write a story, and our beliefs if any will show through "like a body under a blanket". Good advice, partly because preaching bores or irritates the audience like nothing else, so it does not work and will turn away readers. And partly because even the deepest held beliefs can change over time, I know many of mine have!
In a similar vein, Algis Budrys adviced us that long discussions of a philosophical nature does not belong in fiction. He said that there were non-fiction books for that kind of thing, and avid readers of them, so why not write such a one?
Oooh, oooh, oooh, here's another good one (see what I mean about the depth?).
"In the minds of Really Clever Literary Critics, the true worth of a book, movie, or TV series is not in telling an engrossing story with interesting characters, but in allowing people to write long, complex, deep essays on the true meaning of the subject matter, whatever they think that may be. Once the critics have done this sort of analysis, they can objectively declare these works as True Art: it doesn't matter how much you personally like or dislike these works so long as you understand the deeper meaning behind them. Only ignorant fools don't understand."