Sarnsereg, no it gives you additively. Have you ever seen a Standard Touch fail with Steady Hand or a Basic Touch fail with Steady Hand II? They both add to 100%. It's all RNG really. I've had times where I would not fail any 80% Hasty Touch in 10 minutes straight. The assumption that a 70% chance should give a 70% return in a large number of samples is a fallacy.