It's no secret here on the blog that I've written a fair number of books and stories that have all gone into the drawer of practice.
It's all practice and experience. Sure, I could read craft books but they put me to sleep. (Great cure for insomnia.)
That's just not how I learn. I learn from practice, from seeing examples in living color (read: television and movies), and from doing.
I've written three fantasy novels, one steampunk/fantasy hybrid short story (which I later tried to transform into a novel. Still want to make it work), two romance novels, two romance short stories (one of which I transformed into a novel), and done world-building on another fantasy and on a contemporary adventure novel. I've the beginnings of three or four other short stories on my hard drive. Not to mention all the poems.
What's the point of confessing all this? To say this: For the first time in my short writing life (two years I've been going at this in earnest), I feel like I'm finally getting a handle on how I work as a writer and what's going to help me make a book as strong as possible.
When I set out to world-build and plot my latest WiP (and the second and third books in the trilogy), I knew where I needed to improve off my last attempts at writing a novel. Every word I've written has given me experience. Every word has shown me a glimpse of what works and what doesn't. Every word helped me to develop that eye and intuition for character and plot which are, in my opinion, so necessary for good writing and revising.
It may take 10,000 hours to become a master at something, but perhaps it only takes one 90,000 word novel to flip the switch on a lightbulb in the writer's mind.