Is it common to have a set recycled for over twenty years as the Next Generation sets were?

No, it�s not common to have a franchise that lasts for twenty years, either.

When I say recycled, everything gets completely re-designed but you can save an enormous amount of money if you don�t have to re-scaffold a set, for instance. And the studio is always interested in that.

The scaffolds are the catwalks that go above the sets and from which the lighting is generally placed. So that�s why the corridors haven�t changed their shape very much in terms of their floor plan, but the look of the corridors changed from venue to venue.