To start - congratulations on drawing 250 cylinders. It's definitely no easy task, and it can be quite grueling. You've done a solid job of drawing your ellipses - you're keeping them pretty confidently drawn, achieving even shapes, and generally keeping the linework of the ellipses pretty tight as you've drawn through them. You've also done a good job of checking the alignment of your ellipses quite thoroughly throughout the set.

I'm also glad to see that you were mindful of the shift in degree from one end to the other, but there is unfortunately a pretty major issue I'm seeing throughout the entire set. Foreshortening is manifested in two ways. The shift in degree is the less obvious one, which is something we address more specifically in the context of cylinders (though it applies to everything), and you pinned that one down. But the aspect of foreshortening that is generally more widely acknowledged is the simple fact that as an object moves away from the viewer, it gets smaller in overall scale. I'm not really seeing that at all in your cylinders, nor in the boxes for the second part.

This causes two key problems. Firstly, both aspects of foreshortening - the shift in degree and the shift in scale - should occur in equal measure. If the foreshortening is shallow, the far end will be fairly similar to the closer end in both its degree, and in its overall scale. If foreshortening is more dramatic, the far end will be both much wider and much smaller than the closer end. Any inconsistencies where one shift is more dramatic and the other is much less so, will stand out, leaving the viewer feeling that the form feels "off" even if they can't necessarily place why.

The second issue however is that foreshortening conveys to the viewer in rough terms, how much distance there is between the two ends of a form - and therefore how long it is in that dimension. If there is no foreshortening at all, then we're effectively telling the viewer that the form has a length of 0 - an obviously false statement, given that we can see it isn't just a flat disc on the page.

The only circumstance in which a cylinder would have no visible foreshortening along its length would be if it were specifically rotated to run straight across the viewer's field of view, as discussed back in Lesson 1, when a vanishing point "goes to infinity". This is entirely dependent on the orientation of the form relative to the viewer, and is not something we can simply impose on those forms at will. At the very least there should always be at least a little foreshortening. To actively try and keep the edges parallel on the page would therefore be a mistake, and it does seem that this was something you were aiming for in particular.

If we were to compare this back to your box challenge, there you did allow your lines to converge - more shallowly in most cases, but there was visible convergence on all axes. So this may have been a mix-up that occurred between then and now, and it's a good thing we were able to catch it.

Now, in order to make sure that you understand these points, I'd like you to do an additional 10 cylinders around arbitrary minor axes, and 10 cylinders in boxes. I don't think we really need to go overboard with that - the rest of your challenge is looking fine in terms of checking your line extensions in the latter section. But this foreshortening matter definitely does need to be pinned down.