I think the key point is that for any historical site (let’s think in terms of, say, Monticello), there is (1) ongoing maintainance, (2) presentation for the public, and (3) historical projects.
What maintenance is is obvious.
Presentation involves the arrangement of the antiques in the rooms, adding or subtracting to what is being shown in them and on the grounds, the docents who give the tours, the headsets and recordings that you listen to taking the tours, etc.
Projects would be any additional historical presentations related to site that go above and beyond the display of the site itself. So, if you wanted to set up a mural which displayed the story of Jefferson’s relationship with Sally Hemings, the story of their children, etc., that would be one of the projects, I suppose.
At any rate, if you don’t do the first two, you may as well shut down the site; they are necessary. The “projects” are nice-to-haves, not must-haves.