For the first 50, your lines are overall very clean, with only a few traces of arcing here and there, like box 5(15?) and box 32. Your convergences also show good accuracy, though I noticed some lines pair off and converge towards two vanishing points, like box 2(7?), box 24, and box 48. (Though, judging by some of the notes, you also noticed the divergences crop up.)

For the next 50, while a few instances of wobbling and arcing appeared at the beginning, like box 52 and box 69, it resolved early in the set. Most of your lines remained very clean like before. Your convergences also show improvement, though there are more instances of lines pairing off, like box 60, box 84, and box 88.

For the last 150, your lines remain clean throughout the rest of the challenge. Any arcing present is largely minimal. I did see a few points where it looks like a line was redrawn, like box 109 and box 133, but not enough to consider it a major concern. Just keep in mind that, for this challenge, it's better to have one smooth, confident line than to try to fix it by redrawing.

Your convergences show continued improvement; box 245, for example, came out very well. However, there are still instances of lines pairing off, like box 118, box 180, and box 236. In these boxes, the inner lines (green and orange in this diagram) diverge instead of converging at the vanishing point. Keeping in mind the angles of neighboring lines can help when planning the box's construction.

As an aside, box 3 (13?) and box 52 are missing some line extensions. Box 51 has some lines extended in the wrong direction (though it looks like you caught that mistake). It's not a major issue since it only happened a few times, but I want to point it out for future reference.

Also, while it isn't extreme, some of your boxes get a little bit small, like box 46, box 80, and box 244. Drawing larger boxes is more effective for practice, as it'll help you engage your whole arm from the shoulder, and will engage more of the part of your brain that processes spatial reasoning.

All said, you did very well. I'm going to mark this challenge as complete.

(By the way, I like your margin doodles. I'm glad the mascots could keep you company during this adventure.)