hello rgb. I have look over your box challenge and your boxes look good and are drawn with boldness and confidence.but there are a few improvement you can make

Another thing is that some of your boxes where not converge correctly.it seems on some of them you extend your lines the way they were converging while they should be extending towards the vanishing point and not the viewer so we can understand the mistakes were making when making the box and why. this is a common mistake so don't beat yourself up

Another thing is there is a page of boxes that doesn't have their lines extended, you need to extend your lines so you can see what mistakes you're making to help decrease your margin of error

The majority of your boxes have the same amount of shallow foreshortening. The shallow boxes look great but its important to varie between dramatic and shallow foreshortening so you can get more mileage/comerablity in draw those two types

Overall you did fine but they need more work, i recommend you re read the lesson and practice drawing 30 boxes with the critiques i have given