That’s how my current work in process looks.
At the moment I have a lot of stuff that I am 90% sure of, but it remains in flux. What I think is certain at the start may have to be changed by something I add at the end. Or things will need to be added here and there.
It will remain like this until I get to the final stages of editing.
This is an important part of the process for me. The longer I can keep a story fluid, the better.
However, there are exceptions to this.
I find that writing a story is a delicate balance between restrictions and freedom.
The world I am writing in has some fixed rules. For example, despite magic not featuring much in the first book, I already know how it works in the world. I also know how money works, the names of days and seasons. I have a pretty good idea about things like this.
As I work back and forth through the story I will focus more on the smaller things and those things can (and will change) but the bigger things will not.
Of course, once the first book is published, I won’t go back and change anything. At that point even the small things will be fixed. The second book in the series won’t be able to change any of those small things, but it will have its own small things which I will change repeatedly.