Great job on completing the challenge!

Extending lines: at the start they sometimes go into the wrong direction, which could be partially because the lack of hatching making it confusing which side faces you. But you fix this as you go on. Your later boxes all have extended lines that go in the right directions, and you hatch one side. Great!

Convergences: be careful that your lines always converge. They should not go away from each other like in box 236, or go parallel like in box 244. Try to put more preparation into the direction of your lines before you put them on the paper. Follow this tutorial for putting down dots : https://imgur.com/3zoQA65 . Ghost, put down a dot, ghost again, put down another dot… until you are confident the dot is in the right place. Then ghost the line, and then put it down confidently.

Hatching: as mentioned earlier, your first many boxes don't have hatching, but you put it on the latter ones. Although hatching is not required, it is very useful in understanding which side of your boxes facing you. I do notice that your hatching's line quality is not exactly at the same level as the sides of the boxes: lines are wobbly, or faint and arched. Make sure you give them just as much attention as the rest of the boxes: ghost each individually and draw them with focus and confidence.

Line weight: your line weight looks good. It is subtle and confident. Do note that you should not put line weight on the initial Y or the back corner. Line weight should only be on the silhouette of the box.

Confidence: your lines that are not hatching are confident and straight. Great job!

Orientations: you have varied the orientations and extreme/shallow perspective on your boxes well, but could push the orientations a little bit further still. Take this image as inspiration: https://imgur.com/Kqg6uMX

Inner corners: your inner corners are sometimes far off compared to the other lines. This is not too much of an issue, as the back corner is the least important, but one tip that may help is to change up the order in which you draw your boxes like this: https://imgur.com/a/DHlA3Jh . If you follow this order, the accuracy of your back corner will most likely improve a lot!

All in all, great job in completing this challenge. I will mark it as complete, but recommend you to incorporate more boxes into your warming up as you move on to later lessons, keeping this advice in mind.