the ground or me?

Another painting that I am pleased with on my marble dust/gesso ground on rag mat. I'm mixing different recipes to find the ground that will make my paintings paint themselves (haha). But, I think I may have stumbled upon one variable that I hadn't figured into this experiment. I am painting on "scraps," the windows cut from rag mats, and I feel so much more playful (translates to loose for me) painting on them rather than painting on an expensive piece of my beloved Wallis. So, while I'll continue to mix recipes - I have some extra-fine pumice on order - this has led me to another question: is it the ground or is it me?