Starting with your cylinders around arbitrary minor axes, by and large you've done a good job. There is one issue I want to call out, but it was only present throughout the earlier section of this exercise, and aside from that you've done a good job of drawing your ellipses confidently, and checking their alignment with a fair bit of care throughout the set.

So the issue in question is relevant for the cylinders you drew up to august 28th (normally having the cylinders numbered makes sets of cylinders easier to point out, but at least you have the dates on there). The issue here is that it looks like you were deciding not to have your side edges converge towards a shared vanishing point, and instead chose to place that vanishing point at infinity each time. Unfortunately, the location of the vanishing point is controlled by the orientation of the form (or more accurately, the orientation of the specific set of parallel edges in 3D space). While we can control that orientation, we cannot outright say that the vanishing point will be at infinity. It'll only be at infinity when the set of edges itself runs perpendicular to the viewer's angle of sight, so if it slants at all towards or away from the viewer through the depth of the scene, it's going to need a concrete vanishing point. Given that the cylinders for this challenge are rotated randomly and freely, we can pretty much assume that we'll never have them align so perfectly.

Fortunately this was not an issue through the whole set - when you started pushing the foreshortening further, the issue inevitably was corrected.

Continuing onto your cylinders in boxes, I can see that you've done a pretty solid job in constructing these boxes, and in analyzing your results to continue improving page over page. 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.

The only real issue I noticed was a slight tendency to have your sets of parallel lines converge more in pairs as the cylinders got longer. For example, the one on the left side of this page. You're not really all that far off, since the convergence there isn't too significant to begin with, but you do want to angle them towards one another a little more to compensate for the inevitable impact of a longer overall form.

It is worth mentioning that I did notice your ellipses getting more uneven here as well - but that's better practiced with a little more focus on the ellipses in planes exercise when doing your regular warmup routine.

Anyway, all in all, solid work. I'll go ahead and mark this challenge as complete.