Each wafer is printed separately. They don't build new custom production line for each new design.
Its not economies of scale. Why or how would you even etch a worse pattern on the same fabrication node? They don’t even have a mask for the worse version its literally just the same pattern with more defects.
They only make one design because of economies of scale. I think there might have been some confusion here
Maybe you can get more of them per wafer because they're smaller?
Yes but that’s a different thing those smaller chips also get binned based on defects