To tonify Yang Ki, the pressure from the needle should be as light as possible. That means the needle barely touches the skin. Of course, the patient should not feel anything except sensation from the fingers searing points.
However, the pressure from the needle sometimes becomes heavier because I may think it is better for the patient that I have the patient feel something from the needle or simply I'm not careful about the pressure. This is like misunderstanding that if I insert needles deeper, it seems more effective in the insertion needles.
But as a matter of fact, the result of the treatment is much better if the pressure from the needle is as light as possible. Tightness of the muscles loosens up amazingly, compared to the heavier needle pressure. I really have to be careful!