Starting with the cylinders around arbitrary minor axes, I think you've definitely shown a good deal of progress across this set. Earlier on, I could see that you were struggling with your ellipses - you tended to hesitate as you executed them, worrying more about keeping them accurate than maintaining a confident execution and a smooth, even shape. This resulted in ellipses that were wobblier and less consistent, which in turn undermined the solidity of the form. Over the course of the set however, you kept working at it, and seemed to ease yourself into a more confident execution and greater use of the ghosting method, which gradually did the trick. I'd say this is an issue you managed to largely address in the first two thirds of this section, so congrats on that!

I will say though that I think the side edges of your cylinders would benefit from a more intentional use of the ghosting method (being sure to invest that time into the planning/preparation phase and execute confidently for a smooth stroke), as they do appear to be a little less consistent, a little hesitant.

Lastly, you've done a good job of checking the alignment of your ellipses throughout the set, and have even caught some fairly small discrepancies that will ultimately help you avoid plateauing as you get into the "close enough" territory.

Continuing onto your cylinders in boxes, your work here does meet the requirements of the assignment, by and large. 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.

By checking the line extensions, you're giving yourself information on which to base adjustments to your approach, and gradually hone that proportional instinct. There is however two issues that can, and have, undermined how efficiently you've been able to do that.

The first of these is simply to do with the boxes themselves. You definitely need to keep working at your basic convergences, which you can do by being sure to incorporate the box challenge type exercise (line extensions included) into your regular warmup routine (remember that as explained here you should be continually revisiting those old exercises as you continue to progress through the course). We do not by any means expect your convergences to be perfect at this stage, but it does help to have more of that solidified so that here you can focus more on having the ellipses' line extensions converge with a set of lines that are already behaving, rather than worrying about wrangling all of the lines.

The second issue is that there are definitely occasions where you will not identify the minor axis of your ellipses correctly, as shown here for example. If we don't pay enough attention, we can easily just default to assuming that the intended minor axis was the correct one, and as such overlook some pretty significant mistakes. Then if we base our line extensions on that, we'll end up missing important information that could be used to help us improve.

All in all, you're certainly good to consider this challenge complete, but be sure to keep working on the issues I've outlined here so you can continue leveraging this exercise to its fullest effect.