4:30 PM, Monday February 3rd 2020
Sorry, I didn't notice the "view more comments in this thread" button, so I had edited my comment thinking that you hadn't replied yet, but I'll ask my other question here too.
If you're drawing a large cirlce, counterclockwise, in front of the center of your body, and your arm is hanging plumb at your side, don't you have to use both elbow and shoulder movement so your arm can maneuver around your torso? Aren't there times during a motion like this where your elbow is almost touching the side of your body and you're not physically able to move your arm any further using your shoulder, necessitating elbow movement? I feel like this applies to almost all other curved lines too, and that during these, even if the motion starts with the shoulder, you have to add in some elbow movement in order to move your arm around your torso.
The only way I can imagine to make the circle or curved line without using a lot of elbow movement is to either draw the whole thing far to the right of your body, away from your torso, or to hold your arm out in front of you with your elbow bent at a 90 degree angle, which sounds awkward. Is this how you want us to do this?