To start with your big concern, I don't looking at other students' feedback is a problem of its own - it's public for that very purpose, though I don't generally expect students receiving paid feedback to indulge in it, it's mainly there for those who aren't. That said, everything you've described about it does suggest that you're coming at it from a position of fear - fear of wasting time, fear of falling into an intended "trap", fear of looking silly. One of the major pillars of this course is to face our fear of feeling inadequate and of failing, and to allow it to happen. At the end of the day, you'll learn from another's mistakes, sure - but you're going to learn best from your own.

While I do recall the critique you're likely referencing, where I talked about min-maxing, it's also a prominent part of the current Lesson 0 video on Getting the Most out of this Course. You likely won't have seen it because it was released in April, but it may give you a better sense of how to think about your role as a student in this course.

Since you've seen the usual spiel I provide to students, I'm primarily going to focus my critique on addressing your other questions, then call out anything that may have been missed. Oh, before I get to that, the tiny ellipses thing is normal - master ellipse templates are limited by nature, and while they're still well worth using, many students complain about being left to work in a small space. We're working on developing our own to sell as we do pens, but that's still likely a ways off.

So, your questions:

On wheel 8, in regards to that shadow inside the wheel , would that classify as form shading or a cast shadow? The wheel is casting a shadow onto itself, or is it just... absence of light , if that makes sense? for some reason this really confuses me

For our purposes, that shadow would indeed be classified as form shading. While you do raise a fair point about the wheel casting a shadow into that hole in the middle of the wheel structure, the shadow shape itself does not clearly establish a relationship between the form that would be casting it (the wheel's outer structure) and the surface receiving it (the inner rim). You can read more about thinking through such kinds of shadows in this diagram, which addresses "holes" in textural contexts. This diagram also helps a great deal in understanding how to think about tire tread textures that are made up primarily of shallow grooves, where we feel more compelled to represent them as lines (and where in some cases we can even get away with doing so). The critical difference comes down to how we're understanding what it is we're representing, and remembering that a groove is not a textural form - it's an absence of form, with the textural forms in question being the walls around it.

Getting back to your question, generally when you find yourself wanting to draw shadows whose shapes are somewhat more arbitrary, it's a good bet you're working with something that leans more towards form shading. That isn't to say it specifically is the result of form shading, just that in the context of this course, it's not the kind of cast shadow we're looking to use.

when drawing the tread's silhouette, using 18 and 8 as an example, wouldn't outlining the form make it explicit markmaking?

You are - and for an understandable reason - conflating the silhouette of the wheel as a whole, and the silhouettes of the individual tread forms. The outline is not from the tread itself - it's the outline of the wheel. When the tread breaks the outline of the wheel structure, it's going to stick out and have an impact on the silhouette of that 3D structure. Now, if we were to talk about outlining the tread form internally within the silhouette of the wheel, where we would not at all be looking at the wheel's own silhouette, then yeah it'd be explicit markmaking and should be avoided. But that's not the case here.

In cases like rubber,or any smooth surface really, is it possible to texture it,even if there's barely any form to cast a shadow?

What we're doing here is all about conveying information. Our application of texture is not decorative, and so it is not something we add without purpose. A perfectly smooth surface is by definition, a textureless surface. There's no harm in not adding any additional ink or complexity to its surface if it doesn't require it.

Before I call this done, I did want to draw your attention to the fact that while you were aware of the trap, that didn't entirely save you from falling into it. You were certainly more aware than most students, but as shown here, there were some places you drew cast shadows, and other places where you filled in the side planes of your forms. I used number 2 as an example because it was the most prominent, though we can see such cases with 21 as well.

So, I'm going to provide you with an explanation that I've shared with other students, so you may have seen it. It's based around this diagram.

In the top, we've got the structural outlines for the given form - of course, since we want to work implicitly, we cannot use outlines. In the second row, we've got two options for conveying that textural form through the use of filled black shapes. On the left, they fill in the side planes, placing those shapes on the surface of the form itself, and actually filling in areas that are already enclosed and defined on the form and leaving its "top" face empty. This would be incorrect, more similar to form shading and not a cast shadow. On the right, we have an actual cast shadow - they look similar, but the key point to pay attention to is shown in the third row - it is the actual silhouette of the form itself which is implied. We've removed all of the internal edges of the form, and so while it looks kind of like the top face, but if you look more closely, it has certain subtle elements that are much more nuanced - instead of just using purely horizontal and vertical edges, we have some diagonals that come from the edges of the textural form that exist in the "depth" dimension of space (so if your horizontals were X and your verticals were Y, those diagonals come from that which exists in the Z dimension).

With that, I'll go ahead and mark this challenge as complete.