Myth #1: You have to fill in ALL! THE! BEATS!
Truth: No one expects you to know everything about your book before you write it. So focus on what you do know--even if all you know is intangible, like a mood or a feeling--and then start writing. Those blank spots will fill themselves in as you learn more about your book.
Myth #2: Theme doesn't matter.
Truth: Don't overthink or undervalue theme. It is the mirror in which the events of the story are reflected.
I would be willing to wager that all of us, at one point or another, got a quarter of the way through a book and thought, "I understand what's going on action-wise, but I don't know if it's good or bad, or why it matters."
Theme is what the book is about. Theme is the story you're telling, the question you're asking, the point of it. Theme gives us the proper context in which to experience the myriad of events that will transpire throughout the rest of the book. Which is why it's front and center.
The good news is, theme isn't something you add to a book. It's something already there, a question your subconscious keeps trying to answer off and on throughout the story. All you have to do is find it.
Myth #3: If your beats aren't lining up just so, your book is broken.
Truth: SAVE THE CAT is a screenwriting book, and the beat sheet, in its original form is intended to show how one can efficiently squish a story into roughly 90-110 minutes of film. We book people, on the other hand, have a little bit more leeway.
A more accurate way to look at the Save the Cat beat structure is to think of it as a recipe. Here are all the ingredients you will need to make for a satisfying dish. You can flavor to taste.
Myth #4: Some people just don't have the plotting gene.
Truth: Plotting, like most everything else, can be learned. Instead of giving up on plotting altogether, ask yourself why you have such an aversion to it. Is it because not knowing what happens next makes you nervous? Or because knowing too much ruins the story for you?
"That doesn't always work for me" is better than "I can't do it" any day.
Myth #5: "Formula" is a four-letter word.
Truth: Math, science, the universe, and pretty much everything else is made up of some kind of formula. Your DNA? A formula. Your favorite beer? A formula. The way your mind works when coming up with stories? A formula. The beat sheet is no different.
Myth #6: It's impossible to cram the happenings of a 400 page book onto one beat sheet page.
Truth: Can't fit your whole story onto one beat sheet page? Easy. Use more than one beat sheet. Separate your action plot from your romance plot from your subplots and map them each out individually.
Myth #7: This isn't working for me, so I must be doomed for failure.
Truth: Not every book on writing will help every writer. Everyone's different. There are hundreds of books on writing out there. They won't all help you. But a handful will. Keep reading and trying new things until you find them.