Now that I've written three books and am working on a fourth, I've noticed that my writing has improved with each book. It makes sense, of course. Practice is how we learn a skill.
I can't help but notice as I edit The Worlds, my first book, that I'm a lot better than that now. The story is wonderful but in its present form it lacks the depth of the later books. This is a strange thing to discover as I proceed with the editing. I wasn't aware there was such a difference between the earliest and latest books. There is so much more I could have done back then if only I'd known how.
The thing is, I do now. So I'm reinforcing the book as I edit, building greater character depth and improving the story. Another interesting thing is that the last time I read book 1, I hadn't written book 2. Now that the second book is complete I can tailor the first book accordingly. After all, I'm familiar with the next fifty years of this fictional world's existence. I hadn't realized this, going into the edit. It's great.
Looking back, I can see that I was in a race with myself when I wrote The Worlds, wondering all the while, "Can I really do this? Can I write a book?" I rushed to the end like it was a finish line. But times have changed. I can do more with The Worlds now.
In other words, I suspect my 87,000-word book just got a lot longer. In fact, I think I'm looking at a major rewrite. Such is life. I'll do whatever I have to to make my books the best they can possibly be. I owe it to them.
I'd love to hear from other writers about their experiences editing their fiction. See that comment button down there? You can click it, you know.