I am not familiar with that particular book - keep in mind that these lessons are not at all about how to go about drawing with ink - the focus here is always on building up a mental model of how forms exist in 3D space, both at a macro scale with larger constructions, and a micro scale with the kinds of textural forms we instead try to imply. Drawabox is completely devoted to building up this internal grasp of space and form, and every exercise is targeted towards achieving that. This means that you wouldn't necessarily draw in the way these lessons push you to in every situation - it's all about the underlying understanding that it develops in you, which can then be applied more fluidly and organically in conjunction with whatever actual techniques you might learn elsewhere. So, as always, while those external resources are certainly useful, make sure you're not mixing-and-matching approaches and techniques when doing these exercises. To that point, looking at others' work is totally fine insofar as you're looking at the work of people actually going through these instructions, not ink drawings in general, because again the intent and goal may be different.

Starting with your arrows, these are largely well drawn to capture a sense of fluidity to them (especially into the second page), though you do need to be more mindful of how foreshortening applies to both the positive space of the ribbon, which gets narrower as it moves away from the viewer, as well as to the negative space (the distances between the zigzagging sections), which should be compressing at an equal rate. Often times you end up with gaps between those sections that are roughly equal, or even larger than the sections closer to the viewer. It's something that is often overlooked, so just be sure to keep it in mind.

Moving onto your organic forms with contour lines, these are largely very well done, with a couple points to keep in mind. First and foremost, you're doing a good job of sticking to simple sausage forms, but remember that we want the width to remain consistent through their midsections. You do have a tendency to have these sausage forms get a little plump through their middles, which isn't quite what we're looking for. Additionally, you're doing a great job of drawing your contour ellipses and curves with a great deal of confidence, though keep working on getting them to fit more snugly between the edges of the sausage form, so as to lean into the illusion that they wrap around the form more believably.

Jumping ahead to the texture analyses, you're definitely moving in the right direction here with a strong focus on shadow shapes, although you hinder yourself somewhat by relying on hatching lines instead of ensuring that each and every shadow shape is as distinct and clearly defined as it could be. Basically what we're doing here is creating an alternative to hatching - we're producing patterns of dark and light that can be controlled in terms of their density, by using information pulled directly from the reference image. Hatching is on the other hand more generic, and doesn't convey information about a surface. So by including hatching as part of replacement for hatching, we're at least partially missing the goal here.

You certainly do show improvement on this front in a number of places throughout your dissections, especially into the second page. There is still a use of hatching here and there, but you're more often relying on much clearer, more solid shadow shapes. As a side note, when you get into textures that have more distinctly separate textural forms (like pangolin scales for instance), you do tend to fall back on the urge to outline each scale in its entirety, before thinking about shadow shapes. This locks you into a specific level of density, as explained here. You're generally pretty good at avoiding this, but it does come up on occasion.

Continuing to your form intersections, you've largely done a great job of constructing these forms such that they feel cohesive and consistent within the same space, though you appear to have missed the instruction about avoiding forms that are overly stretched in any one dimension, like longer cylinders. Be sure to stick to more equilateral forms, ones that are roughly the same size in all three dimensions. You've got an excellent start on the intersection lines themselves. These serve as an early introduction to the concept of thinking about how forms relate to one another in 3D space, and how these relationships can be defined. This is something we'll continue to explore throughout the rest of this course, but you're already showing considerable comfort with the idea.

Lastly, your organic intersections are looking great. You've got a clear demonstration of how these forms interact with one another in 3D space, rather than as a series of flat shapes stacked on a page. You're also conveying a strong illusion of gravity in how they slump and sag against one another.

All in all, great work. I'll go ahead and mark this lesson as complete.