>>5978356i did the exercise where you traced the lines and realized a few things:
1) you need to tape all of the corners of a loose sheet of printer paper to keep it from moving
2) you need a stool or a chair with no armrests to draw from the shoulder and avoid the temptation to start drawing from the elbow
3) your shoulder will become very tired quickly which is exacerbated by the fact that you are trying to very lightly drag the tip of the pen across the surface of the paper
4) drawing over the same line repeatedly makes it hard to tell if my lines are wobbling subtly due to drawing too slowly (my lines look tighter than than in the example video for all it's worth)