Hey, congratulations for making it through.

In my opinion your boxes have improved a lot. Linework has leveled up substantially. Kudos Perspective wise you have improved for sure but I think you still have to go a little further. The back side of your boxes is usually your weakest side and where you get divergent lines at times.

A few tricks I used to get better that you can try and see if they help you are:

  1. Try to visualize the whole box before drawing every edge. I tended to fix in too much on individual edges and didn't see the big picture until it was drawn. Usually, erroneusly.

  2. Always follow the same process. Is much easier too find where you are deviating if you always follow the same steps. I drew the 2 front faces first, then the hidden "base" of the box and then the rest. But that is just and example.

  3. After drawing the visible edges I drew the "ghost" points for all hidden edges at once and used (1) to see if they where good.

I would continue using the boxes as a warm up until you nail that perspective. But don't let that stop you and continue to lesson 2.