Cute

I think this is great! My only suggestion would be to take time at the end like Stan mentioned and look missed lines. But I personally like how deliberate you were with the piece and your line work. Doesn't look like there was any underdrawings which is crazy to me, because you got the image and proportions. Something I could never do without using the Loomis method. Keep it up!!!

Sorry to hear you've had things get in the way of drawing. For what it's worth, you've got the box outline in all of these well in hand. All the boxes feel well placed spatially. The only critique I have is that the lines inside the boxes don't follow the perspective of the box, going a little crooked in some places where they should cut across the shape in the same way as the edges of the box. Keep at it and fit in this kind of practice wherever you can. Using shorter and faster things like this can help you to build up your understanding for drawing in the limited time it sounds like you have. Good luck and thanks for sharing!

I agree with your assessment, though I think they all show the potential for growth. In addition to what you said, I would say for the 5 minute sketches, you show slightly too much focus on the surface forms and contour. They are fairly gestural, and sometimes when one had 5 minutes, it can be tempting to add those to the figure. However, if you are trying to practice gesture and rhythm drawing, it likely will not help very much. However, your 30-second drawing looks to me to be an excellent example of what this exercise is looking for, and certainly looks well-designed.