Starting with your cylinders around arbitrary minor axes, for the most part your work here is well done. I did notice that you weren't always the most consistent in ensuring that you were drawing through your ellipses two full times before lifting your pen (you did so more often than not, but there were definitely cases where it dropped to 1.5 turns or less, which while not a huge problem does suggest a decrease in focus on each individual task you're performing). I'm pretty pleased with the linework otherwise - your lines are straight and smooth and your ellipses are fairly evenly shaped, although when it comes to the use of the ghosting method I'm not seeing signs of the planning phase where, when drawing straight edges, we plot the start/end points down.

It's clear that you're still holding to the main principles of the method, but keep in mind that everything we do throughout this course is meant to be extremely intentional (rather than slipping into automatic behaviours) so that when we draw outside of the course, we can rely confidently on our instincts and allow our muscle memory to take over on all that. When we do that during our homework however, we end up developing those habits less firmly, and we leave some of that habit-training on the table rather than ensuring we're getting as much as we can out of the work we're doing.

Aside from that, solid work here - you're checking your minor axes fastidiously throughout the set, and catching not only more obvious misalignments, but you're also attuned to some of the minor ones that can easily slip beneath the radar and be missed. Keeping an eye out for those seemingly less significant ones is important, and what you're doing here will help you avoid plateauing as you fall into the "close enough" territory.

Continuing on into the cylinders in boxes, it does make sense that you found it challenging to draw the front/back planes as perfect squares, because that is precisely what this exercise is meant to help train. To say it more directly, 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.

So you're not really expected to be able to do that right off the bat, but rather it's what this exercise is meant to help us improve at. And for the most part, it certainly does appear to have helped you in that regard. You're applying the line extensions correctly, and the main issue they tend to reveal (not in all your cases, but in a number of them) is where the longer your cylinder/box gets, the more prone you are to what we call having your lines converge in pairs.

Basically these boxes have planes on either end, and each plane is made up of two lines from from two of our sets of parallel edges. So for example if we look here at 191, each end has two blue lines and two green lines to form a complete plane.

Of course, when we're plotting out these lines, we need to be thinking of all the blue lines together, and all the green lines together, so that despite coming from opposite ends of the box, they still converge towards the same point. But the longer that box gets, the more inclined we are to just focus on the lines that are close together, resulting in the blue lines from the top plane and those from the bottom plane aiming for largely different vanishing points, and therefore not representing edges that are parallel in 3D space.

This is a common issue, and the main thing is to be aware of it happening so you can consciously adjust how you approach drawing those edges going forward.

Aside from that, you're applying the exercise effectively, and I can see improvement in your ability to estimate those planes' proportions to keep them square in 3D space. I'll go ahead and mark this challenge as complete.