Starting with the first section of the challenge - the cylinders around arbitrary minor axes - one thing immediately stands out, that you haven't been drawing through your ellipses. As introduced back in Lesson 1, you should be drawing through all of your ellipses two full times before lifting your pen, whenever you freehand them throughout this course. I appear to have called this out in relation to your Lesson 3 work as well. Drawing through your ellipses helps lean into making more evenly shaped ellipses, while also providing us with more muscle memory training to that end.

Moving on, I also noticed that while you did draw the red/blue lines over your ellipses to check their "true" alignment, the lines you were drawing for each ellipse's minor axis was off fairly often. Here's an example page where I've marked out those that were immediately noticeably off.

In general, I really get the feeling that the work here was rushed. This challenge - which as mentioned at the top of the challenge notes, is recommended to be done between Lessons 5 and 6 - is quite demanding, and takes a fair bit of care and patience. It also benefits from a fair bit of mileage with using ellipses in general, hence coming in much later in the course than the box challenge.

Continuing onto the cylinders in boxes, it appears that you've missed a pretty important part of this challenge. 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.

While you were very fastidious in checking the line extensions for the boxes themselves, you don't appear to have applied the analysis of the ellipses' line extensions, and so you didn't actually check this aspect of the ellipses, which was demonstrated both in the video, and here in the notes.

Normally at this point I would ask for a full redo of the challenge, but as you opted to complete it way earlier than necessary, I think it would be best to call this a bit of a wash, and have you continue onto Lesson 4 as instructed when I marked your Lesson 3 work as complete. You will have to do the challenge over once you've finished Lesson 5, but you should have more mileage with ellipses under your belt at that point, and will hopefully go through the instructions a bit more closely then as well.