Let's take a slight detour. I've started a new drawing. This, of a great blue heron that we saw at the San Diego Zoo. Since the discussion has been about pen strokes, this is a good example of stippling. The short feathers under the heron's head are done with dots or very short strokes. Further down the neck, as the feathers get longer I move to longer strokes. (click on the image to enlarge it).