Now, self, when you follow all those previous notes and have yourself a great chapter all outlined and thought out, when you know your characters and can predict their every move, when your plot is a shining jewel just waiting for a setting—things will still go awry.
It's okay. Just press delete and try again—and again. And again!
See, the truth is, nothing's written until it's written. A scene that feels like it makes perfect sense might come out all wrong because of one little thing—like it has too many characters, tries to do something it shouldn't, or on second thought, no, that character wouldn't actually say/do/ingest that no matter how much you need them to.
Writing novels is easy. Writing good novels—that's hard. Some chapters are simply harder to get right, and it never gets any easier. Does it mean they don't belong? Sometimes. But not necessarily. Some things require sustained effort and long periods of meditation in a hot shower.
Note to Self: When your plans go wrong and nothing feels right, keep going. A small change might make all the difference. Other times a large change is required. In the end, you've got to keep going until you're satisfied—or there's nothing left to try and no new ideas at hand. Then you've got to try again, just to be sure. As your marching band director always said, "Leave nothing on the field."
(He may have been reminding us to jam our mouthpieces in really hard.)
(Yes! A dash in every paragraph.)