9:36 PM, Wednesday September 15th 2021
Your boxes are pretty good, and feel believable. I definitely see improvement in the perspective from the first batch to the last batch.
A great many of your boxes have a common problem though where the two edges on the same plane of the box converge, but they do not converge with edges of the planes on the other side. Take a look at this imgur album showing boxes 84, 241, 203.
In 84, the 2 blue lines comprising the top plane converge, and ditto for the bottom of the box, but they do not all meet.
In 241 and 203, same thing with the blue lines.
Your problem, as I see it, is that you're not considering the box as a whole and instead drawing each plane one at a time. Because your convergence is alright when considering one plane but it's the other 2 that give you trouble. Just slow down a bit maybe, and try ghosting the lines more to ensure both sides of the box are converging.
Aside from that there's not too much variety here. Almost all your boxes are like 2/3rds profile view. Try more weird positions and angles. There are many times when you'll see a box and only be able to see two faces if it splits the horizon, or it's near the center of the camera. Like a fridge, a refridgerator is a box but if it's taller than you, you will never see more than 2 faces of it at once. Try drawing that and seeing if you can get the perspective right. Try to think of practical uses of a box for drawing. How would a skyscraper look if you represented it as a box? Or a train, your fridge, or your keyboard in front of you? You could also try taking a box you've drawn and rotating it along an axis just slightly, to force yourself out of your current comfort zone.
As you draw more from reference you will naturally learn about these situations though.
Final thing, your line quality is definitely improving but you also have a tendency to pet your lines and overshoot your mark. Just keep working at it and it'll get better. My advice is always just to slow down and get into a nice rhythm. Draw a line like you would pet an animal, nice, long, slow movements.
Your boxes definitely got more consistent as you progressed though. I feel like you understand the source material so I'm gonna say you can advance, but I would recommend drawing more boxes in weirder positions like I mentioned above.
Next Steps:
Draw more boxes, or better yet, draw real objects from reference that are boxy . Get a better feel for the different ways a box can be rotated and positioned in 3d space.
