To answer your question, you are permitted to resubmit lessons for feedback, but when it comes to doing so for specific lessons you feel you want to revisit, it's not really something I'd recommend. The main reason for this is the way in which the course is designed - it's not attacking a bunch of individual problems in each lesson, but rather tackling the same core problems in each lesson (especially lessons 3-7). Furthermore, remember that the feedback we provide is subsidized, so unless there's a good reason to do so, it would draw on the resources that are generally allocated towards keeping the cost of feedback low. Of course, if a student has taken a long break and wants to take several steps back and continue from there, that's entirely acceptable - but there's not really much to be gained from deciding that you weren't satisfied with how you tackled a particular lesson.

Anyway, getting into your cylinder challenge, there are a couple things I noticed in regards to the first section that I want to call out. Overall your linework is pretty decent - you're executing your marks with a fair bit of confidence, although I do want to urge you to make a point of following the specific steps of the ghosting method, as described in Lesson 1, more closely so as to avoid little wobbles or areas of hesitation. It's easy to forget to apply every aspect of the ghosting method intentionally, and to slip off that track. Ultimately throughout this course we push students to be extremely attentive to every choice they make throughout the process. In so doing, they get enough exposure to it to actively alter their instincts, and the result is that when doing their own work, they'll be more likely to take a split second to consider the nature of the mark they wish to make, rather than rushing ahead into it and hoping for the best.

Another point I noticed was that you don't seem to have varied your rates of foreshortening all that much. While there are a number of cases where you appear to keep your side edges entirely parallel on the page (which is its own issue), it's hard to say that this specifically comes from you intending to keep those lines parallel, or if you're trying to maintain very shallow foreshortening throughout and are making them too parallel as a result.

While making them entirely parallel on the page is actually incorrect, and I'll explain why in a moment, the instructions for the challenge are quite clear in asking you to vary your rate of foreshortening throughout the set.

As to why having your side edges entirely parallel is incorrect, when representing edges in 3D space as lines on a flat page, they converge towards a vanishing point. We don't control where that vanishing point falls - not directly, at least. What we control is how we wish our form, and by extension those edges, to be oriented in space, but it's this orientation that dictates the position of the vanishing point. It's only when the edges in question run perpendicularly to the viewer's angle of sight - in essence where they're not slanting towards or away from the viewer through the depth of the scene, just running straight across their field of view - that the vanishing point goes to infinity.

Since in this challenge, just as with the box challenge, we're rotating our forms freely and randomly in space, we can pretty much assume that the cylinders won't align so perfectly to the viewing angle so as to push the vanishing point to infinity.

Continuing onto your cylinders in boxes, your work here is considerably better, and more in line with the instructions. 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, you're giving yourself ample information to help assess how successful the previous page of boxes were, so you know how to adjust your approach moving forward. Over time, this hones your instincts regarding your judgement of proportion, helping you to assess what proportions would result in a square regardless of how it's oriented in space. This should continue to be useful as you progress through the rest of the course.

Before that however, I am going to require you to do some revisions for the first section. You will find them assigned below.