Matt,
One famous gca's son told me that his father had exactly 19 basic holes. I think a bigger pallete is required - at least 35 or so would be enough to provide some design variety over a career, after fitting each hole concept to the site, which should entail minor changes.
Another way to look at it is to break concepts into "bits". Does, for example, a Redan have to occur on a par 3? Does a Cape Hole always need to be on a par 4? Does an inside fw bunker complex always need to have the green bunker on the outside? If your formula calls for heavily bunkered fw to be followed by a lightly bunkered green, can you do an appropriate hole with heavy bunker both places? Etc.
Also, at least one new idea should be brought in to each course, either by truly using the unique features of the site, or building something out of the box, or even by combining tried and true elements, like Fazio's cape hole with a tree on another thread.
That's design evolution and brand safety mixed into one package.