Keep one writing project, but create different visual workspaces for different questions.
One map is useful until it becomes a warehouse
A map for the whole book may contain themes, chapters and major relationships. Add research, character networks, one complicated plotline and the internal logic of Chapter 8, and the board begins to lose meaning.
Different maps can answer different questions
One board can show the whole manuscript. Another can focus only on one character network. A third can collect research for a nonfiction chapter. A fourth can be a temporary workspace for a difficult restructuring problem.
This is not duplication
The important part is that the boards can point to the same real project entities. A chapter shown on two boards is still one chapter. You are changing the view, not creating another source of truth.
assets/img/bmaker/bmaker-explained-multiple-maps-01.webpTemporary boards are allowed to disappear
A visual workspace does not have to become permanent architecture. Create one to solve a question, keep it while useful, and stop using it when the decision has been made.