Which branch in the Project Browser cannot be organized with an organization scheme?

The Legends branch in the Project Browser cannot be organized with an organization scheme because it serves a specific purpose in Revit. Legends are used for providing visual reference for items such as annotations, symbols, or model elements used within the project. Unlike other branches, which manage broader categories of project elements and can be organized in various ways (like by name, type, or based on specific parameters), Legends are typically standalone views that illustrate specific information pertinent to the design but do not lend themselves to different organizational schemes.

In contrast, Schedules/Quantities, Sheets, and Views can all be arranged according to organization schemes. For instance, Schedules can be organized by different parameters such as category or type of schedule, Sheets can be grouped by their sheet numbers or types, and Views can be filtered based on view types (like floor plans, elevations, etc.). These functionalities enhance the clarity and manageability of the project's components and help in streamlining the workflow for users.