hey there Bones, I'll be the one looking over your submission today but before starting I'd like to congratulate you on finishing the 250-box challenge, it's a very daunting task and you've managed to push through! This just shows your eagerness to improve and i'll be looking forward to your next submissions.

so let's get started

starting off with your lines, you're off to a good start! your extension lines are all extended in the correct direction, and it's also extended to certain extent which will tell on either how off or how close you are on converging them, one minor issue though is that in some boxes, you crossed them off... i'll... let it slid- or would I? I know that these are all minor slip ups as the boxes 53 and above are all extended correctly, but i have one thing to point out, when you have this minor slip ups, it's better that you try to work with it since in future lessons when you try to either correct it or hide it it will most likely make it worse(which will make it more noticeable) or hide it(which will most likely make it so that you'll have a hard time knowing it's a mistake).

As you progress throughout the challenge there's no doubt that you got better! your mark-making, your hatching lines' consistency, tightness and confidence; the convergences on your boxes got significantly better, you've also experimented with a good amount of orientations, length, sizes for each box; you've also followed the instructions of the challenge which is to do both shallow and dramatic foreshortening, so great work!

moving on to your convergences, in some cases there are parallel/ diverging extension lines while in other cases there are lines that converge by pair, keep in mind that a set of line should be converging into a single point not onto multiple points (you can look at this image here which tells on how a set of line actually relates with angles), neither will it diverge away from the vanishing point(because if it does diverge then it isn't a box and more of a trapezoid or a pyramid) nor will it be parallel due to perspective(because it'll be called isometric perspective which isn't a true 3d object), but it's quite hard to get all set of lines to converge into a single point so it's not expected that students would be able to get it on their first try not even after finishing the 250 box challenge.

overall you've done a wonderful job in this submission, there's still room for improvement but you seem to get the gist of what this challenge is about, you also did your best of your current ability and you've gained mileage. don't forget to add this exercise to your pool of warmups and once you're more confident, you can start doing the advanced box exercises for your warm-ups.