Howdy, TA qzhans here!

Before we begin, I just want to congratulate you on giving those 250 boxes a good ol’ pen and ink smackdown. It is a MASSIVE undertaking and you’ve joined the prestiged club of its completers.

You’ve painstakingly drawn through all your boxes and extended every single last line out to check your errors, and your boxes have been better for it. Indeed, you’ve made a marked improvement throughout the set in terms of your understanding of convergence.

The main issue that concerns me here is your line quality. I'm seeing a lot of re-drawn and patched up lines, despite the majority of your linework being fairly straight and accurate. I thought that this may have been some lineweight gone awry, but a lot of the times, you're thickening lines on the invisible, back end of the box, instead of the visible silhouette. Remember that all lines we put down are law, and laying down more lines to fix something will only create more contradictions and draw eyes to a mistake. Attempt each line only once, and then work around it if it was a little flawed.

Also, although you've done a pretty good job with convergences, some of your middle back lines are still stubbornly not jumping in line with the rest of them. That’s okay, and is something that gets ironed out over time, but I’ll offer some advice. When you go to draw a line, think only about the lines that are supposed to be parallel to it (share a vanishing point). Lines closer to an existing line will converge slower, while the opposite is true for lines further away.

A few that you didn't do could help you when practicing convergence. First, it'd be a good idea to draw your boxes bigger; I'd say 6 is the maximum amount of boxes you should be fitting on a page. This actually helps get more accurate boxes because your margin of error increases by a lot. Second, you should also extend your error lines out 2-3 times the original line length, crashing into other boxes if need be. Finally, it'd be good to try out less isometric boxes first, and try ones with noticeable convergence first, as these are little easier to verify visually that they're converging.

Overall, I think the skill is here, but the mindset could be dangerous if I let you go on, especially in terms of linework. Thus, I'd like to see 10 more boxes from you before I let you move on.