Hi, I’ll be critiquing your 250 box challenge

Lines

As you said at the beginning the line-work wasn't really good, but it got better as you gone on; remember also to avoid trying to correct strokes by adding other lines.

You are using hatching correctly, the line quality looks ok, but it could be of better quality, take your time when hatching and don't rush it.

Box Construction

You have applied the line extension method correctly and all of your sets of lines converge, but make sure to have the extension line and the original edge of the box well aligned, in some of the it isn't.

There is a good variety in boxes angle, sizes and vanishing point distance, it's a nice thing that you've experimented with them.

I can see some problems with converging in pairs and diverging lines, but these errors got less and less frequent as you gone on, so I think you are on the right track for fixing them, or at least you're well able to see them.

Aside from these issues I think you've done a good job and I belive you will continue to improve with practice.