Stages can be defined at three levels — the workspace, the project, or the individual folder — and a folder ends up with whichever set applies to it. That resolved set is what you actually see on the board.

The point is that you set them once at the level where they are true. A team whose work always goes through the same four steps defines them on the workspace and every folder gets them; a single folder that genuinely works differently defines its own and overrides the rest.

When a new folder is set up it takes a copy of the level above rather than starting empty, which is why a fresh folder already has sensible stages before anyone configures anything.