So unfortunately, my critique is going to be something of a mirror image of your own self-assessment, and in that spirit, I think I'm going to start my critiquing your cylinders in boxes first.

Despite your worries, you mostly did a great job at this exercise, and the reason for your confusion is that you simply didn't fully understand what it was for. This was mentioned in the video for the challenge (as well as here in the notes), but it's not a big deal that you missed it. What's important is that despite your confusion and uncertainty, you followed the instructions to the letter, and as a result, you did the exercise correctly.

This exercise is really all about helping develop students' understanding of how to construct boxes which feature two opposite faces which are proportionally square, regardless of how the form is oriented in space - it's actually much more about the boxes themselves, rather than the cylinders. We do this not by memorizing every possible configuration, but rather by continuing to develop your subconscious understanding of space through repetition, and through analysis (by way of the line extensions).

Where the box challenge's line extensions helped to develop a stronger sense of how to achieve more consistent convergences in our lines, here we add three more lines for each ellipse: the minor axis, and the two contact point lines. In checking how far off these are from converging towards the box's own vanishing points, we can see how far off we were from having the ellipse represent a circle in 3D space, and in turn how far off we were from having the plane that encloses it from representing a square. From there, we modify our approach (that is, modify how we draw the boxes), and try again.

There are some places where your misunderstanding of this threw you off - for example, on this page, you were no doubt frustrated with the fact that your ellipses' extensions weren't lining up with the criteria of that which represents a circle in 3D space, so you started drawing them independently of the box's own proportions. This resulted in your extensions behaving better, but they effectively disconnected the analysis from the box itself, so wasn't too helpful in the context of this exercise. Fortunately you switched back to the correct approach after that, and held to it throughout.

There were still some that were way off in terms of their proportions (like cylinder 34 on this page), but as you progressed through the set, your proportions did indeed get better and better, and I am fairly pleased with how it all turned out. You may not be entirely aware of how your work has progressed (probably because you spent most of it unpleasantly confused as to what this was all meant to achieve), but that didn't stop you from benefiting from it.

Now, unfortunately the first section of the challenge - the cylinders around arbitrary minor axes - was not quite so well done. There are aspects of it that are coming along well, of course. Your ellipses are coming along nicely, in terms of the confidence of their execution and the evenness of their shapes, though there is still a touch of hesitation so keep pushing yourself to employ the ghosting method (to avoid second-guessing yourself during the execution of the mark), and also be sure to engage your whole arm from the shoulder while drawing each ellipse. You're also doing a good job of checking the alignment of your ellipses by marking the true minor axis line in blue. All of that is coming along well.

The big issue however comes from the fact that aside from the very first page, you ended up actively trying to eliminate the convergence of your cylinders' side edges, effectively putting that vanishing point at infinity. This unfortunately is fundamentally incorrect - the position of the vanishing point is determined by the orientation of the lines it governs in space. It will only go to infinity, resulting in no actual convergence on the page, when the given set of lines runs perpendicular to the viewer's angle of sight (rather than slanting towards or away from the viewer through the depth of the scene). This means that the cylinder itself would have to be aligned in a relatively specific manner each time. Given that this challenge has us rotating our cylinders freely in 3D space, we can pretty much assume that this perfect of an alignment would not occur, and that we should always consider some amount of convergence for those side edges.

This lack of convergence also messed with the impression of foreshortening that was portrayed in these cylinders. As requested here in the assignment section, I did want students to play with a lot of variety throughout the set, ranging from dramatic to shallow (though still non-zero) foreshortening. Foreshortening itself manifests in our drawings in two distinct ways - there's the degree shift, which you generally handled just fine (having the ellipses get wider as we slide farther away along the length of the cylinder), and there's the scale shift (which is a direct result of the convergence of those side edges, resulting in the far end being smaller in overall scale than the end closer to the viewer).

When these two shifts occur independently of one another - for example, having the far end be much wider, but not any different in scale, or vice versa - the viewer can pick up on this as a general sense of the cylinder being "off", even if they don't know exactly why. It occurs because one of the shifts tells the viewer there's lots of foreshortening (suggesting that more of the length of the cylinder is hidden in the 'depth' dimension of the scene), and the other one tells them that there's minimal foreshortening, and therefore they're more or less seeing the entire length of the cylinder. This is a contradiction, making it difficult to pin down the cylinder's length and orientation in 3D space.

So, to put it simply, by forgetting to vary your foreshortening, and by actively trying to avoid the difficulty of dealing with your vanishing point, you ended up side stepping a major aspect of this challenge. I can fortunately say that based on your cylinders in boxes, you are entirely capable of handling your vanishing points and foreshortening very effectively. This is simply one of those cases where something slips our mind, or we miss something important, and it takes us somewhat in the wrong direction.

In order to address this, I'm going to ask for some revisions - it crossed my mind to have you redo that entire section of the challenge, but I don't think that'll be necessary. You'll find the revisions assigned below.