Superimposed Lines

• Try and make sure your starting positions are closer together. Accuracy to reduce fraying at the end comes over time, but accuracy when starting the lines is a mental thing, prepwork! See: https://drawabox.com/lesson/1/9/fraying

Ghosted Lines

• Looking good! Confident lines.

Ghosted Planes

• All good here! Perhaps try and be a bit more daring with the shapes, a lot of them approach squares. But that's nothing too serious.

Tables of Ellipses

• Nicely done. 2 loops everywhere and pretty accurately touching the edges as well.

Ellipses in Planes

• You're undershooting more often than you're overshooting. They definitely look fine, but if you're trying to improve, consider correcting towards overshooting so you'll end up in the middle.

Funnels

• Properly angled, well on the lines, and not misshapen to correct. Nice!

Plotted Perspective

• No mistakes :)

Rough Perspective

• Try and keep parallel lines properly parallel. You're sticking to the confident lines which is great! It's indeed better to leave mistakes for what they are and salvage what you got- but try and salvage it in such a way that the new lines you place are "correct" again, don't compound the mistakes into a slanted whole. See: https://drawabox.com/lesson/1/16/guessing

Rotated Boxes

• Looks great on first sight, but the back-face of most of your squares aren't actually rotated. You did it well on the front-facing cubes, apply the same idea to the back-facing ones as well!

Organic Perspective

• Make sure to give each mark an equal amount of attention, I can tell you started going fast here. All parallel lines will converge into the same (imaginary) vanishing point, but some of these cubes don't. Also be wary of foreshortening, it will make some correct cubes look messy as well. See: https://drawabox.com/lesson/G3SI84C/7/foreshortening

Overall

Good stuff! Most of the critique is relatively minor, nothing to redo here. You have pretty good accuracy.

If anything, make sure to keep your head on and stay focused for all the exercises. Especially when it comes to perspective, even though some part is freeform, a lot of it can still be deduced, it's not guesswork!

PS: As for training shoulder control, I got nothing. Stay aware of it and steer back whenever you can tell you're going from your wrists or elbow. Consider joining the discord and asking the same question there, more people will read and react!