If a material has no reflection or refraction. Can i set the subdivs to 1? do they have to remain 8? Is the 8 subdivs “inactive” until you set a reflection/refraction colour?
If there is no refl/refr (color = black) then the subdivs won’t have any effect. The same is true for any and all sub parameters of an item that is disabled. So you can safely just leave them as is 