Hey there I'll be handling your 250 box challenge critique.

I'm glad you're putting in the effort to redraw your lines less.

Pat yourself on the back for completing the challenge, it takes a lot of discipline and willpower to sit down for days and draw all 250 boxes.

Overall you have shown quite noticeable growth through the entire challenge. At the beginning your boxes used to twist and skew quite frequently, and while not perfect all the time by the end we don't expect perfection (we're humans after all) the important thing is you have become much more consistent and clearly grasp the 3D space you're working in. I feel like your first step in improvement occurs around box 120 while the second noticeable step occurs around 200, from here on your convergences become more consistent and your linework tidies up a bit, even your hatching becomes more consistent and less wavy. (Looks like it may be time for a new pen though.)

You do still have some instances of your lines diverging or converging in pairs rather then all together, so I'd like to point you to this example. It shows how a set of lines relate to their related vanishing point. The inner pair will nearly always be identical but the outer pair may vary quite a bit depending on how close the vanishing point is to the box. The further the vanishing point is from the box the closer to parallel each pair of lines becomes.

I feel you've shown enough improvement for me to mark your submission as complete and move you on to Lesson 2.

Great work so far and good luck.