Grats on finishing the box challenge! Overall you've done a pretty good job. You drew the boxes super big which is great, and your convergences improved a lot through the challenge.

The things I can catch is that when you were applying hatching, you were rushing it a bit. Don't forget to start your lines in the corners of the box, so the lines don't fray in 2 ends.

By the end of the challenge like I mentioned, your convergencces improve a lot. But they still have issues, specially with the inner corner. This is completely normal, but here are 2 things that helped me to get it better:

This order of drawing boxes, and this diagram. Thinking about the relationships between lines instead of thinking in pairs will make your convergences be much more accurate, so give both of those a read and try the new order.

Overall like I said pretty good job!