When should I use navigation sub-folders?

Navigation sub-folders should be used if you have a navigation topic that contains more than one file:

Otherwise, if your subfolder only contains an index file (imagine the screenshot above WITHOUT the ..._subflder_content_page and ..._external_link), the url to this file will be something like, ..../navigation_item1/nav_item1_subfolder/index.html.

Instead you should simply use a content page directly under the navigation_item1 folder, so the url will be shorter, .../navigation_item1/nav_item1_subfolder.html, where nav_item1_subfolder is representative of the name of the file.

For example, the following shows an expanded top-level navigation folder (research) that contains only content files (no navigation subfolders).

Alternately, if subfolders had been used, there would be a current_studies subfolder containing only an index file.  The corresponding url's would look like this:

With a Navigation Subfolder:  ..../research/current_studies/index.html

Without a Navigation Subfolder: .../research/current_studies.html