Hi Ladondelphi i am trollfromhell and here is my critique of your 250 boxes exercise

1.extending lines

you are doing a good job by extending your lines towards the vanishing point just make sure your lines converging to one vansihing point and the more you draw boxes the more you will get better at putting these lines to that VP

2.hatching lines

 this is optional but since we want to make it look 3D it would be better if we put hatching lines on the side of the box where the viewers see the box and apparently you don't put hatching lines 


apply lineweight one 1 side of the boxes to make the viewers think we are looking from that side of the boxes 

check this out https://d15v304a6xpq4b.cloudfront.net/lesson_images/980a575e.jpg

4.use dots

apply dots when u are not sure where u want to put ur lines when forming boxes coz i see some over extended lines

5.some repeating lines

 when you make a mistake when putting lines, no need to repeat drawing a line to fix it coz you end up putting lineweight and breake the cohesion of the boxes (the 3d effect) so avoid it at all cost

6.Similar orientations with boxes.

most of your boxes look similar in a way their vanishing points are close to the object and it implies we are looking a very   tall object so i suggest try drawing boxes with shallow vanishing points (vanishing points are far from the object) 

Here's a diagram that shows different orientations of boxes, so check it out to get some ideas. Keep in mind that in the box challenge you should always draw from imagination, not from reference, so don't use them to copy.


7.inner corner

it's pretty common to see mistakes when putting the inner corner lines,one way to solve it is to start thinking lines in pairs so basically the further the box is from the vp,the lines will look parallel just look at this https://i.imgur.com/8PqQLE0.png

you can also try drawing the inner corner of the boxes before drawing the last line https://imgur.com/a/DHlA3Jh

also can you do me a favour ??? i need 1 agreement for my 250 boxes submission : ) https://drawabox.com/community/submission/LVP3J18

lastly i want u to try drawing 30 boxes more with shallow vanishing points and with hatchings and line weights