Hey akinay83, great job completing the challenge. You've definitely made a lot of great progress here.

To start off, your overall line quality and execution has improved by an order of magnitude. By the end your lines are much more controlled and confident. You have a good exploration of space with your boxes in terms of convergences and orientations, and the only thing I would have liked to see is some larger boxes so keep those in your warm up routine as they help for the later lessons.

Your convergences are improving greatly, and by the end of the challenge you are really in the zone. This

infographic was made to further expand on the topic of convergence and for those who really have trouble with the "back lines" of boxes. You don't necessarily need it but I will link it here for completeness. The gist of what is being conveyed here is all parallel lines are to be treated as an ensemble because they all impact each other. The angles between them are related to the location of the vanishing point and as it moves the angles all change. When drawing boxes we cannot draw any one line without thinking about its impact on the other parallel lines which you have done a great job of here. In terms of finding things to improve on, you could have worked on applying line weight on the silhouette of your boxes to make them feel more solid. Overall though you have done everything asked of you in this challenge and I will be marking it as complete. Great job!