Overall excellent job and great improvement! You've clearly learned a lot from pushing through this challenge. I'll start off by telling you what I think you did well:

Overall your hatching is very excellent. You used a large number of lines on the face you choose to hatch and they are all very straight and accurate. I've seen people utilize scribbles as their hatching before, but its very clear you understand the importance of practicing your ghosting. In terms of box lines, they all appear very straight and accurate, like you knew exactly where you wanted them and really took the time to make sure they were accurate. This is a great habit to keep up in the future. Looking from the first boxes to the last, It's clear your general sense of perspective and convergence has improved as well; all your lines generally converge and hit the same place on each box, and its evident that you tried varying box shapes and perspectives to broaden your skills. You did a very nice job.

As for criticisms, there are a few key things I believe you can improve on. The most obvious is that you put too many boxes on each page, assuming you used standard 11 by 8.5 inch printer paper. Its better to draw roughly 4-6 boxes per page so that you have more room to experiment with box shapes, sizes, and other various factors. I complimented you on your hatching earlier, but on boxes 70-109 you started using a gray marker for shading? Maybe you were just experimenting, because you switched back later, but I just found that slightly odd. In terms of line weight, you could've put a little more on your boxes, especially as you approached the end; your clearly capable of making straight, precise lines, so it wouldn't have hurt to just put a little more weight on the outside of the box. On a few boxes you have lines that are meant to be on top of one another that don't exactly line up right, making the box look slightly sketchy (box 232 bottom plane for an example). I know its tempting to fix a mistake with other lines, because I did that a lot on my challenge, but from what I've learned it's a bad habit going into the future.

In terms of just general tips that I would tell anyone that helped me personally, I have a few that could maybe help your art endeavors in the future. I would watch Uncomfortable's second video on drawing a box every now and then to check improvement/refresh your memory on tips you might have missed. You could also watch Scylla's box drawing tutorial or Uncomfortable's review of their 250 box challenge. Another good resource is Proko's video on drawing boxes, spheres and cylinders. I'll link all of these below, if you haven't already seen them. As for stuff I learned, it can be useful to rotate your box as you draw it to better see the places where parallel lines converge.

Good luck in the future!

Proko: https://www.youtube.com/watch?v=3uEtdDvK6Xo

Box tutorial: https://www.youtube.com/watch?v=jlJ6rwj3PKg

Scylla's tutorial: https://www.youtube.com/watch?v=mteUPdCHn4s

Scylla's box review:https://www.youtube.com/watch?v=vxXPY6XnCmI