[Request] At what rate is electricity discharged in the following situation?

Take a sweater that will generate static electricity if you rub it. You rub it for x time, then touch metal, and you feel a shock. You rub it for 2x time, touch metal, and you feel a greater shock. But if you are constantly touching the metal, a shock never builds up. Does the building up electricity discharge one electron at a time, or do they build up and discharge at some other rate?