Hi, I'm glad you have completed the challenge.

You yourself will be able to notice a great improvement from the first box to the last.

The convergence of the lines to the vanishing points is just right.

Even the back corner is aligned in most of the last boxes (which is good).

The only corrections I can give you are regarding the lines themselves.

In some boxes it looks like you tried to apply line weighting and crosshatching. It is very good to perceive the orientation of the boxes.

Although it is very good, you should avoid tracing the line weight many times in the same line, once you do it will be enough, the line weight must be subtle to work.

And regarding crosshatching, try to make sure that the hatching lines reach the edges correctly. I mention this because in some of your boxes the hatching lines seem to fade before touching the other end.