Congratulations on completing the 250 Box Challenge!

You did a pretty good job on your boxes as a whole. I can see that you took your time and were careful when constructing your boxes. Your mark making stays clean and confident throughout the challenge, which is great to see.

I can also see that you tried experimenting with adding weight to your lines and while at first you appear to struggle a bit, by the end you do a much better job of getting your added line weight to blend seamlessly with your previous work. Your boxes also do a better job of getting your sets of parallel lines to converge consistently towards their shared vanishing points.

One thing that you should do in the future is try drawing your boxes much bigger than you did here. In the instructions you are told to fit five or six boxes onto each page. This is to allow you room to draw larger boxes. Drawing bigger helps you engage your brain's spatial reasoning skills, whereas drawing smaller impedes them.

Finally while your convergences do improve overall I think this diagram will help you further develop that skill as you continue through Drawabox. So, when you are looking at your sets of lines you want to be focusing only on the lines that share a vanishing point. This does not include lines that share a corner or a plane, only lines that converge towards the same vanishing point. Now when you think of those lines, including those that have not been drawn, you can think about the angles from which they leave the vanishing point. Usually the middle lines have a small angle between them, and this angle will become negligible by the time they reach the box. This can serve as a useful hint.

You did very well overall and I can see you improved and learned a lot by the end of the challenge. Keep in mind what I have said here and you should continue to improve!