Hello there ramelone, good job on completing 500 boxes! This is definitely not a small task and you should take pride in your work. Let's get to your critique.

Even though you went through the challenge once before, you have grown a lot in this set of boxes. In the beginning your lines were really messy and not though out - lots of redrawing lines and an overall lack of planning but by the end you were really putting down some crisp, confident marks (although 247 is pretty suspect). Your sense of space also improved indicated by your more regularly converging lines.

In terms of your convergences, you are starting to hon in by the end of your boxes. For the most part you are doing a good job viewing your parallel lines as a tandem and not worrying about things like locating the back corner but rather focusing on guiding your lines toward the vanishing point and letting everything fall into place. Uncomfortable has made this infographic that goes more in depth on the matter, and since there are some skewed lines still going on I'll go over it a bit. When you have parallel lines in perspective, it means they are all connected to one another by the vanishing point. As the VP moves, the angles between all these lines move. It's attention to these internal angles that is key to making sure your lines track correctly towards the vanishing point. Another way I explain it is you have to "step back" and view all of your parallel lines simultaneously, both drawn and yet to be drawn ones. As you step back you can make sure all of your angles are appropriate, as illustrated in the infographic. It can be quite difficult to do this at first but as you mindfully practice it, like any other skill, you will get better at it.

That being said, you drew your boxes, you applied your extension lines, and you have shown substantial growth throughout the challenge and I will be marking it as complete. As you move on to the next lessons which lean towards organic subject matter, make sure you continue to practice boxes in your warm ups so you don't get rusty. I also like to suggest starting to practice larger boxes (1-2 per page) so you are ready for lessons 6 & 7. This is because larger boxes have their own unique sets of challenges.