5:16 AM, Wednesday April 14th 2021
Congratulations on finishing the 250 Box Challenge.
First I want to say your lines are very good and confident. The correction lines are extended correctly. In some of them, hatching lines are rushed, so next time take your time with your hatching lines. If you draw your hatching lines more carefully, the box will appear more clean and solid.
I see a lot of parallel lines and divergence. Don't forget, in 3 point perspective, every set of lines should converge to a specific vanishing point. They can't be parallel or diverge. Every three sets of 4 lines will converge towards a single vanishing point. In the boxes where you apply more foreshortening, the lines converge more, but when you apply little foreshortening the lines become parallel, or they diverge. You can check this explanation to understand the convergence better. Also, this order of drawing boxes may help you with the inner corners.
I would recommend you check the lesson material and the lesson video one more time to understand the convergence and then make 12 more boxes. This time it might be better to change the variety of boxes and draw fewer boxes on one page. It might be four boxes per page. This way you can see how the extended lines converge or diverge better.
Next Steps:
Check the lesson materials one more time and after that draw 12 more boxes.