The option is designed to delete any folders and/or files that are not associated with an item in the Shared Documents table. There are no time limits or definitions associated with the Cleanup Documents function and all documents that are not linked to a shared document are deleted from the server. For example, if an assignment with a shared document is deleted and the shared document remains in the Downloadable Documents folder, the Cleanup Documents function will delete this document because it is no longer linked to an existing assignment in FAWeb.