I am fascinated by Tolkien's writing process and mind as well. I recently read the article about "Bamfurlong", its a place in the books that didn't really need a name. Nothing about the name influences the story at all, the name didn't even appear in the first edition.
But he HAD to go back and add that name in later editions because this place and its history was SOOO real to him.
For every story we got from him, he must have built a hundred more in his imagination of that place.