While your pacing (especially the 150 across 2 days) is a little worrying, your work is generally well done, so it seems you've largely held to the responsibilities of giving each mark as much time as it requires, despite cramming it all into such a small space of time. Starting with that first set of 150, you're doing a good job of executing your ellipses confidently, achieving even shapes, and your side edges are generally fairly consistent too. I do notice some smaller hiccups with those on occasion (mainly cases where they might arc slightly, or have a slight hook to the end of the stroke, otherwise not being perfectly straight, though fairly close). This isn't a big concern, but I did want to call it out as I did not see the usual signs of applying all of the ghosting method's steps (namely putting points down for the start/end of your intended stroke during the planning phase) - just in case in reflecting upon how it was approached, you may have been able to invest more time into that part in order to yield yet better results.

In terms of the cylinders themselves, you've demonstrated a good understanding of how the degree shift changes as the physical rotation of the cylinder does, and have appropriately ensured that it operates in tandem with the shift in overall scale from one end to the other. Both of these shifts convey the rate of foreshortening to the viewer, so the demonstration that you understand (whether consciously or subconsciously) that they should operate together is good to see. I'm also pleased to see that you've been quite fastidious with your error checking, identifying both more obvious as well as subtler discrepancies. This should help you avoid plateauing in the "good enough" area, and continue improving with practice.

Continuing onto your cylinders in boxes, your work here is similarly well done. 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.

In applying the line extensions correctly and thoroughly across the set, you've continually given yourself ample information on how your current approach can be adjusted, allowing you to then make those adjustments in the following page and then analyze those results in turn. This back and forth analysis, though it doesn't have us actively thinking about the proportions of the boxes themselves, helps to improve our instincts in regards to achieving squared ends, and looking at your work I can see that your sense of such proportions has developed quite well. This should leave you well equipped to tackle the last couple of lessons of the course.

So! I'll go ahead and mark this challenge as complete. Keep up the good work.