Starting with your cylinders around arbitrary minor axes, the set starts out with a bit of an issue, whose frequency reduces as you progress through the set. The issue in question is essentially where you tend to draw the side edges of your cylinders parallel on the page, as such avoiding having them converge and conveying no actual shift in scale from one ellipse to the other to convey the foreshortening applied to the form.

While I do see students start out this way towards the beginning, in most cases they either keep doing it through the whole set (in which case they get some pretty heavy revisions), or they do it up to a point and then stop doing it entirely, likely from having noticed these notes from the instruction addressing the issue. In your case, you certainly eased up on it pretty soon, but it does continue to show up here and there, in cases like 32, 34, 40, and others towards the beginning, as well as 119, 120, 137, among others. This suggests that while you understood the necessity of varying your rates of foreshortening, you may not have gone through the notes I linked. As such, you should definitely give them a read to better understand why forcing the vanishing point to infinity given that we're rotating these forms randomly and arbitrarily in space would be incorrect.

Continuing onto your cylinders in boxes, it definitely started off rocky, especially on the first page. Here on this first page it seemed like you weren't entirely sure of the orientation of the boxes you were constructing, and so you frequently put the end of the cylinder that would face the viewer (based on the addition of hatching) in the plane that based on the convergences would have been the far end of the box. This resulted in all kinds of confusion, on top of which I also noticed cases where you drew your ellipses such that they did not touch all the edges of the plane enclosing them - we can see this in cases like 2, 4, 5, 8, and 9 to varying degrees. Past these first couple of pages it comes up far less frequently, but it is still present in 19, 20, 72, etc. but the further we get into the set the more it seems like your intent was to have the ellipses touch the plane's edges, but that you simply missed. That would be pretty normal, and would not be an issue - so I'll interpret this as though you caught this issue yourself, and tried to correct it, which is all I can really ask of you.

Ultimately, 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. 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.

It's for this reason that having that ellipse fit snugly within its enclosing plane, touching all 4 edges, is so important. This allows the ellipse to describe the plane's proportions, and so it allows the line extensions derived from the ellipses to be used to gauge whether or not those proportions are correct.

Anyway, over the course of the set you've definitely shown a great deal more improvement, and I can see a clear focus on using the information derived from the line extensions being actively used to improve your proportions. There's certainly more room for further growth, and it is important that you continue practicing these kinds of things in your warmups (I do get the impression that you might be a little lax on those warmups, which may contribute to the weakness we see towards the beginning of the sets). All in all though, I think you're demonstrating an understanding of what these exercises are aiming for, and the capacity to apply their instructions correctly.

So, I'll go ahead and mark this challenge as complete.