10:40 AM, Wednesday April 15th 2020
First of all, congratulations on finishing the 250 boxes! They really are a pain in the ass to do, and you managed to push through all of them.
I'm glad to see you've been taking the time to extend the lines on all your boxes and to hatch the planes on them. The correction lines themselves are applied correctly, and I can definitely see improvement over the whole set.
However, you've been drawing your boxes way too small, and you haven't drawn almost any shallow foreshortening box. Shallow foreshortening boxes are boxes which have their vanishing points very far away. And as it's written on the box challenge's lesson, most of your boxes should consist of them. These boxes are specially important, and it's because of that why I want you to do 30 more boxes before marking this as complete.
When drawing those boxes, I want you to do a maximum of 4 boxes per page. Occupying with them as much space as you can. Don't worry if the extension lines collide with other boxes, and be sure you are drawing every line with your shoulder.
Next Steps:
Draw 30 more boxes, maximum 4 boxes per page, and draw them so they occupy as much of the page as they possibly can. When finished, reply to this comment with your revisions, good luck and keep it up, you're almost there!