First off: congrats on getting through all 250 boxes!! This is no small feat and your improvement over the course of the set is quite tangible.

You do start out with a pretty strong sense of 3D in your boxes - your convergences are pretty tidy, even at the beginning, but as you get towards the end, they become much more consistent, with fewer stray lines and steadier divergences. Your line work improves substantially as well. At the beginning, your lines are actually looking quite feathery and pretty wobbly on a lot of your boxes. This improves pretty well towards the end although I recommend continued practice with the ghosting technique in order to smooth that wobble out. After you've smoothed it out, you can hone your accuracy with the intial line and your super imposed lines.

We link these notes at the end of every challenge as a matter of course. They go over the angle of each line as they approach the box and how keeping an eye on this could improve your convergences. Also, considering each line in relation to the lines with which it shares a vanishing point rather than the lines with which it shares a plane or a corner could do the same.

Overall, really strong work here, both in terms of improvement and in getting through the challenge!