Well done on completing 250 boxes and getting it done in only a month.

Looking through your submission, it seems like there were a few issues that persisted through most of your boxes. The biggest one I notice is that almost all of your boxes have pretty dramatic perspective, with the vanishing points being close to the boxes. In some cases, one or more vanishing points was closer to the box than the others, resulting in corners with angles less than 90 degrees and boxes that looked distorted. If you're practicing some more with boxes, try drawing them with faraway vanishing points, even stretching off the page, and try keeping all the vanishing points at similar distances from the box.

The other issue I notice is that you were getting mixed up with your convergences and where the corners should be placed. Sometimes the groups of lines were converging in the wrong direction, or the back corner threw you off. This is something that it looks like you were improving at on the last several pages, but if you haven't already, I'd suggest taking a look at ScyllaStew's video on her approach to the box challenge. She chooses the position of the corners by ghosting out edges and then placing dots where she thinks they'd intersect. Then she makes sure the corners all intersect nicely in the center before she places the back corner.

One other final critique is that your lines have a bit of wobble to them and the hatching lines aren't always going at the same angle.