With lots of pages in a site, setting up navigation requires a balance between overwhelming users with too many pages, and making it easy for experienced users to find particular pages that they know are on the site.
Working within the Fermilab theme, it is possible to have subpages only appear when you click on the high-level page.
For example, instead of having:
It is possible to move these lower-level pages under a medium-level page.
The drawback is what to put on the top-level page and the medium-level page?