11:13 PM, Wednesday March 24th 2021
Drawing from the shoulder to me means that the shoulder is not locked in place. It can freely move in conjunction with the elbow and wrist. It helps you to not rest heavily on your surface to draw.
Take the simple act of drawing a 6 cm circle on paper in one fluid motion. Your shoulder provides most of the range of motion required. The elbow compensates a little for the shoulder and the wrist is essentially locked. If you lock your shoulder you can't draw it. The same can also apply to straight lines or curves. The shoulder does the heavy lifting, the elbow fine tunes and the wrist is essentially locked.
It takes practice because you are not used to using your shoulder this way. Strength and control take time to build. The good thing is that it scales and allows you to draw bigger shapes much more confidently .
I have got to the stage where I barely think about it now but I still do my shoulder warmups every day. I follow these exercises. I have started doing them on my Cintiq and iPad Pro as well as paper. Paper and sharpie is still the best practice though.