Hey Darius.

I highly recommend that you redo some of the boxes and draw through the lines with another colored pen or even a graphite pencil. This minor thing would drastically improve an understanding of how vanishing points work and improve your boxes, which is arguably a very critical part of learning how to draw. When you were using a pen in your earlier boxes I noticed a good pace of improvement with drawing them in proper perspective. However, later on, it seems that you began to stop drawing the lines back and the box quality began to look rushed or inaccurate. Don't forget to ghost your lines as well. Unfortunantly, drawing isn't a speedrun and just filling out the 250 boxes without understanding is not going to make them better.

My recommendation for you is to draw another 50 boxes and this time be sure to draw the lines out to find the vanishing points. Good luck!