6:49 PM, Wednesday September 2nd 2020
Looking over your cylinders constructed around arbitrary minor axes, there's a number of things that immediately jump out at me that I want you to keep in mind:
First and foremost, you're drawing pretty small. Each of these cylinders have ample room around them, and they're each kind of crammed into a much smaller space than is actually needed. Drawing small (as may have been mentioned in the past) is a great way to hamstring your brain's spatial reasoning skills, whereas being given ample more room to think through spatial problems is of considerable benefit. Conversely, students often draw smaller when they're lacking confidence, as it feels like it'll make things easier - though more often than not it makes our drawings more stiff and a little more clumsy, in part by limiting how easily we can engage our whole arm while drawing.
Secondly, you seem to have focused primarily on very shallow foreshortening through the first chunk - whenever doing any kind of exercise that involves repetition, you want to focus on lots of variety. You varied the orientation of your cylinders a fair bit (albeit more in the two dimensions of the page, not playing so much with cylinders that were oriented more towards or away from the viewer (where the ellipses on either end would be much wider, and overlapping one another), but it wasn't until past the 100 mark that you actually started exploring different kinds of foreshortening. I am however pleased that you eventually became aware of this shortcoming and corrected it.
Because you did eventually incorporate more foreshortening, it brought to light another issue. Take a look at cylinders like 132 and 133. Here you've got the overall scale of the ellipses shifting smaller as we move from the closer end to the farther one. Unfortunately this is only one of two aspects of foreshortening - the other is the rate at which the far end's degree widens in relation to the closer end. In this situation, the far end should also be considerably wider than the closer end. Both of these kinds of shift (one involving scale, one involving degree) suggest a longer length to the cylinder, as they become more extreme. If you have just one of the shifts pushed to an extreme, but not the other, then that introduces a contradiction to the drawing.
Moving onto the cylinders in boxes, one important thing about this challenge is that it's more about learning to draw boxes that themselves have two opposite planes that are proportionally square (for either end of the cylinder). We train this similarly to how the box challenge gradually improves our ability to judge convergences, by checking those alignments after the fact and then making adjustments to our approach. In this case, we merely add additional lines to those extensions, relying on the fact that only when the ellipses themselves represent a circle in 3D space will their minor axes and contact points align to the same vanishing points as their container box.
Top that end, I do see a fair bit of improvement in your judgment of those proportions. That's not to say there isn't plenty of room for improvement - this is a difficult task after all - but you're headed in the right direction. One thing to keep in mind most of all however is that when you get into longer boxes/cylinders, you tend to forget that the sets of lines on either side of the box must still converge towards a shared vanishing point. You instead tend to have them group off into two more distinct sets. For example in 249, we can see blue lines go off into two separate groups.
All in all you are making progress, and have shown definite improvement over the set. I'll go ahead and mark this lesson as complete. Continue to incorporate these kinds of exercises into your warmups, however.
Move onto lesson 6.