I think what most of us want is that potentials do not get raised at all by using/eating herbs.
I ate about 6 morgia root, uncertain about B/U/C. Was very disappointed when my Toughness potential went up. I have noticed that a bit more is required to raise the stat itself. Which is going to make it even more unlikely for an unspoiled player to discover the secrets of stat training herbs.
One can harvest infinite amounts of herbs which is the problem with them raising stats, the result is that every character ends up with Wi, Dx, To at 25+ in the early midgame.