Hi I'll be critiquing your 250 boxes today

First thing is I noticed popping up is the way you went about making your boxes. You tended to make a lot of them parallel or diverging when it came to vanishing points and convergences. When drawing boxes in 3 point perspective, remember that all sets of lines must be converging together, they're all traveling to a vanishing point in 3 perspectives.

Your extensions can sometimes go in the wrong direction such as box 21 (which is also a box with convergence problems). Remember, when extending our lines for correction we want them to go Away from us in order to find how the box converges in space.

Your hatching is something I notice aswell in your boxes, even all the way to the end. They come off rushed compared to the actual boxes and their own marks. When hatching, remember to take your time making your marks. You have the ghosting method for a reason, to plan and execute your marks with confidence, this goes for details such as hatching the outer side of a box.

Your inner corners to your boxes could use some work, but that's not entirely on your fault. It's just something that everyone trips up with when tackling boxes. The very best thing to do about it is to worry about it last when drawing your boxes, it is a symptom of how you're drawing the rest of the box and can distract you from the more important marks you'd be making.

Besides those three, you did a decent enough job throughout the challenge; your main marks for your boxes comprising the outline of the box are all confident which is already a good step forward, and your box orientations are pretty varied. Your lineweight could be slightly more prominent, but that's a minor thing in the grand scheme of the challenge.