Terry Brooks advises novelists to write an outline before writing a novel. He does acknowledge that many successful writers write without outlines. Then he says:
But if you check what most writers who don't outline have to say about their work habits, you will discover that they end up doing several drafts of a book and any number of rewrites afterwards.I don't. I do one draft, one rewrite, and I'm done.
By outlining, you are doing the hard work in the beginning--the thinking, the organizing, the weighing and considering, and the making of choices. By doing it early, you can save yourself a lot of time and effort at the end. [Sometimes the Magic Works, p 95]
I don't think Brooks's advice fits for me.
I wrote my first novel in November as a NaNoWriMo project. In the month before, in October, I prepared by writing a partial outline. I sketched out 20 or so scenes. Most of these were action scenes, in which a viewpoint character tries to accomplish some goal, bumps into a conflict or obstacle, and (usually) ends up worse off at the end of the scene. For those scenes, I noted the goal, the conflict, and the outcome.
A handful of scenes were reaction scenes, in which the viewpoint character reacts to a setback, ponders the available options (usually all bad), and makes a decision about what to do next. For each reaction scene I noted the reactions, the options, and the decision.
Those 20 scenes seemed like a great beginning for the novel--they left the main character on the edge of his sanity. But I didn't know what would happen next. I put in a lot of thought, but couldn't think of anything that satisfied me. I had a vague idea or two about the ending, but I didn't know what would happen in the middle of the story. I ended October with a detailed outline for the beginning, an idea or two about the ending, and no clue about the middle.
On November 1st I began writing the scenes I had sketched in the outline. On most days the words flowed well. Other days the words came slowly. But they always came.
Somewhere around the 14th, I ran out of outline. But I kept writing, and the ideas kept coming. On most days the words flowed well. Other days the words came slowly. But they always came.
By the end of November, I had written about 18,000 words according to the outline, and another 34,000 words without an outline. Mostly my process stayed the same, outline or not. And the quality of my writing stayed the same. And my hopes and worries about my writing stayed the same.
So it isn't clear to me that the outline helped, or that it saved me any time.
My first draft, at 52,000 words, is just barely a novel. It's certainly not a good novel. It is sketchy. It's full of holes. The characters do a few things with little motivation. In a few places, I made characters do downright stupid things in service to the ending I had cooked up ahead of time. I have a lot of work to do to flesh out the story and make it satisfying. In a sense, my first draft is not much more than a detailed outline.
It's possible that this first draft gave me no better understanding of the plot--the main events of the story--than I would have gotten from completing the outline. Even if that's true, I'd still prefer the writing, for two reasons. First, as much as I enjoyed outlining, I enjoyed the writing far more. That counts for a lot.
Even more important is this: As I was outlining--thinking about the story--I had a general sense of who the main characters were. But I didn't have an experience of the characters no matter how much I thought about them. It was only by writing them into trouble, and writing their reactions to the trouble, that I could decide who I wanted them to be.
As I outlined, I thought about the plot and the characters. As I wrote, I experienced the the characters. Experiencing was better than thinking, in the same way that eating a strawberry is better than thinking about eating a strawberry.