Hello Ferretonfire! Glad to see you're enjoying it! The shoulder thing eventually becomes subconscious as you keep reminding yourself to do it, so keep it up!

For the 50% drawings you can draw however you want, wrist or whatever you want, on any tool or medium you want, no restrictions.

Now let's go through the exercises! Overall you've done a good job, though there are some things I want to talk about. Let's go through them section by section:

Starting with your lines you're overall doing a pretty good job committing to your lines and drawing them confidently even if you're going to miss the ending dots, which is great!

On the superimposed lines your lines fray on both ends, whenever you are starting a line you should carefully place your pen on the start of each line so only a maximum of one end can fray.

Last thing is that you aren't drawing starting and ending dots on each line you draw on the ghosted planes. Be careful with that as it's pretty important for applying the ghosting method!

Moving onto your ellipses you're also overall doing a good job drawing them confidently, though they do get wobbly at times, and their shape starts getting a bit non symmetrical. I know it's hard, but make sure you always visualize the shapes of the ellipses before drawing them, it's super important.

The ellipses also get a bit too inaccurate at times, so make sure you are always aiming for the ellipses to touch top and bottom lines and to touch other ellipses in the tables of ellipses. Make sure you also ghost every ellipse until you're confident as well! Take your time with every one of them.

This applies as well to the ellipses on ghosted planes, which I think they're a bit wobblier than the others. You might be thinking that the centre of the ellipses is the same as the centre of the planes or that you should modify the elliptical ellipse shape so it touches the contact points, but this is not the case. Ellipses have to be symmetrical and have the same form regardless of where they are, so the only things you can change is how wide the ellipse is and which position it is in.

Lastly on your funnels sometimes you aren't aligning the ellipses to the minor axis. Make sure you always aim for the ellipses to be cut symmetrically by the middle line even if that means you need to ignore the initial curves. Pay also attention to the angle of the ellipses as well. They have to be cut symmetrically by the line, so they can't be tilted.

Finally in your boxes a few things:

-Your lines start to get a bit wobbly consistently unlike previously, your first priority with lines is to make them confident and straight just like in the lines section, so focus on that first and don't worry if you need to sacrifice accuracy to achieve it.

Here's one example, top line is a level 1 line, and bottom line is a level 0 line. This is because a confident line will always be better than a wobbly line in these exercises. In general try to approach them just like an individual ghosted lines exercise. Remember that these boxes don't have to look good, they're just practice for yourself. So if they help you get better it doesn't matter how they look!

-Sometimes you repeat lines that were off. No matter how off a line is do your best not to repeat it, keep going as if it was correct as redrawing them will make the drawing messier and can encourage bad habits.

-On rough perspective you aren't extending the lines of the boxes correctly. Remember you need to extend the lines of your boxes with a ruler regardless of the vanishing point how far the lines are from the vanishing point when extended will tell your where your mistakes are, that's the whole meaning of this correction method.

-On rough perspective as well you seem to have trouble at times keeping height lines perpendicular to the horizon line, and width lines parallel to it. I know it's hard, but make sure you always are aiming for it. You can check if the starting and ending dots are correct or not, and if you find that they aren't you can change them. You can put down as many dots as you want as long as it's before drawing the actual line, so give it a shot!

-On rotated boxes you've done a good attempt keeping boxes together and rotating some of them! Main thing is that you haven't drawn fully all of your boxes. Try to think how many lines each box has (12) so you never leave one part of a box undrawn. In future attempts pay attention to the rotation of the boxes as well as some, specially the ones on the outer ends, aren't rotating.

-Lastly on organic perspective you're doing a good attempt overall apart from the line issues! The boxes have perspective issues but that's not a problem as you'll work on them through the box challenge. I also recommend you add lineweight to the outer parts of boxes that overlap. It will help to clarify which boxes are on top and which behind.

That said, overall you've done a good job, but I want you to do one more page of rough perspective before moving on so I know you know how to apply the line extensions correct and that you can draw confident lines on boxes as well as you did on lines. Good luck and give a reread at the page of the exercise before retrying! Keep up the good work!