For a forum type service that has a calendar, files section, photos section, etc, we use a sidebar on the left side to provide navigation to these pages. The sidebar has about 13 items, including Admin for people with administrative privileges. When clicking Admin, it opens a dropdown secondary menu with 13 additional items. Finally, some of the pages provide access to additional, related, pages via buttons horizontally across the top of the page.
It's a lot of items, and not everything is easily discoverable (you have to know to go to Admin -> Settings page in order to find the Export Group function). And the horizontal buttons aren't great on mobile, where we collapse them to a dropdown.
If we pull every single page into the sidebar, that will get very long. Do we do some sort of accordion to collapse related items in the sidebar to make things more manageable? Do we instead do a modal for the Admin pages so that we have a separate sidebar just for it? Or something else?