Looking at the first section - the cylinders around arbitrary minor axes - and comparing its first half to its second half, I think there's definitely a pretty significant improvement. Especially early on, I'd say that your linework tended to be much more hesitant, with perhaps less mindful use of the ghosting method to achieve confident executions, resulting in lines that weren't quite smooth and straight, and ellipses that weren't as evenly shaped as they could have been. I'm very pleased to see that degree of improvement.

I'm also pleased to see that you played with variety, specifically in exploring both cylinders with shallow and dramatic foreshortening. This is something I request specifically because it allows me to identify certain kinds of issues and misunderstandings specifically relating to how foreshortening manifests in a form.

Foreshortening can basically be seen in how the two ends of a form differ from one another. In this case, the ellipses on either end shift both in their overall scale (far end being smaller than the closer end), and in their degree (far end being wider than the closer end). What this means however, which students sometimes miss, is that the rate at which both of these change should be quite similar. You shouldn't end up with situations like cylinder 143 for example, where the far end gets much smaller (suggesting dramatic foreshortening and more distance between the ends), and where the far end also maintains a fairly similar degree/width to the closer end (suggesting shallow foreshortening, and a smaller distance between the ends). This results in a contradiction that tells the viewer that the cylinder is both long and short simultaneously. While the viewer won't necessarily know precisely why this looks off, they will be able to tell that something doesn't look right. So, be sure to keep that in mind moving forwards.

Moving onto the ellipses in boxes, for the most part you've done a good job, being extremely thorough in checking the convergences of your lines. Those line extensions are critical to the purpose of this exercise - specifically to develop the student's instincts for drawing boxes that feature opposite ends that are proportionally square. We do this by using the fact that an ellipse's own lines (minor axis and the lines defined by the contact points) will only converge towards the box's own vanishing points when they represent perfect circles in space. The closer we get to having those lines converge consistently, the closer the ellipses are to representing circles - and therefore the closer the planes enclosing them are to being proportionally square.

Now, I did catch the odd case where your line extensions weren't quite correct - for example, with number 65, your minor axis for the front-most ellipse was off by quite a bit (although the rear one was spot-on). These are the correct ones. As a result, even though your line extensions suggest that it was all done quite well, it could have been inspected more closely.

Anyway, all in all your work throughout this challenge is pretty solid. As such, I'm going to go ahead and mark it as complete.