I'm glad you stuck with it too! You've done a great job here.

You have made a lot of good progress here and you have gone through an interesting exploration of form and space. Normally as students progress they become more aware of converging lines and their boxes start to reflect that, but in your case as you progress you start to reign in your convergences and start targeting more distant vanishing points (almost too little convergence on some boxes resulting in orthographic perspective, but we'll get in to that in a minute). So your line quality starts off already pretty good, and by the end it's even better as indicated by your hatch lines as they were the only wavy lines to begin with, really.

Alright, let's move on to your boxes themselves. Right at the start you were being mindful with trying to get your lines to converge, and while things were somewhat off and askew this was a good start; much better than ending up with just parallel lines with no conscious effort to make them converge. As you progress and start to get a feel for things you start making more natural (read: less extreme foreshortening) boxes and by the end you may have gone a little too far on the other end of the box spectrum with little to no convergence on them. That's ok though, learning is done through exploration and you've done a great job varying you orientations and convergences throughout the challenge to really get a wide set of boxes under your belt.

Regarding your back line convergences you are doing a very good job by the end keeping them in line with their neighbors for the most part. Just to really hammer things home though I am going to share the infographic that uncomfortable made to further expand upon drawing parallel lines in perspective. The crux of the matter is never drawing any one line without consideration for all of its parallel neighbors. They are all related to one another via the vanishing point and the distance of the VP determines the angles between these lines. When drawing a box often times we start with the Y then we choose a plane and make sure the two pairs of parallel lines in that plane are all good and converging well then we move on to the next plane and repeat this process in a vacuum with no regard to the first plane drawn. This results in skewed back lines and multiple points of convergence. Overall though you are on the right track with this.

You have made great progress, followed all directions, and shown clear growth in this challenge so I will be marking this as complete. Congratulations!