Hello Congrats on completing the 250 box challenge.

First of all wow, these are some really nice boxes and you have really good confidence in your lines However I do think there are some areas you might be able to improve which hopefully I can give some relevant advice for.

The first thing I can mention is the cross hatching you have done on the faces of your boxes are a bit wobbly and they really take away from the edges you have drawn. try to use the ghosting method for these lines too which will make them more confident lines.

In terms of your boxes converging the lines you have draw seem to be mostly parallel, while this makes for good looking boxes try to experiment with some dramatic foreshortening and some lines which converge quite a bit more. Also all your boxes are looking pretty much the same, here is an image Ive taken from Elodin to give you even more box variations.

another tip I can mention is that you can increase the length of your line extensions a bit more to get a better visual on your convergences, it doesn't matter if they go over the other boxes or cross over some of the other extensions.

the last thing I should mention is that you dont need to cross out the lines like you did on page 223-228 its ok if the box comes out incorrect. doing it like that makes your drawing come out messy. You didnt really do this anywhere else but I thought it was worth bringing up.

I dont think theres really much else to say other than maybe try out some of the advanced box exercises

It seems you already have a good grasp on 3d space which will help you alot in the next lesson. Good Luck!