Hi, IarinaM.

Overall they are good. As stated by The_Desert_Vixen, in some occasions it seems like you've rushed, but, in the end, you managed to keep them mostly clean, which is a good thing.

One thing I noticed is that even after your 200th box, you still struggled sometimes to select which plane to shade. For example (this is only for your 200+ boxes, but it still happened before these), your 205th, 206th, 230th and 236th boxes have the shading on the back planes. Check here what you did wrong and see if this helps. The front planes are the ones that are touching the edges of the front Y.

Also, that inner corner seems that is still a challenge for you. One thing that helped me was to place all the dots before drawing any line. It's not easy, because you'll have to find the the perspective before drawing a single line, but in the end, you can look at all dots and find if there's any major perspective issues. Then you can correct the dots and draw all the lines. Some people also prefer to draw the inner corner right after the initial Y. These are two methods that you can try and maybe they'll help you with it.

Because there are not severe issues with your boxes, feel free to move on to the second lesson.