1 hour session

The 25 minute sketch is very good, it captures the flow of the pose and the shading very well. There is very little I have to critique on that, except perhaps a lack of detail in the hand. But in 25 minutes you can only do so much, so that's totally just nitpicking.

Your 5 and 10 minute sketches are lacking the same flow though. Don't get me wrong, they're not "bad" at all, but compared to your 25 minute sketch they look like disparate shapes cobbled together. I would suggest trying to focus on the flow of the figure a little more at first when doing short sketches like those. Try to capture the "line of action" before just blocking out the wedge of the limbs (no pun about the website we're using intended!)

Here's a great overview: https://www.joshuanava.biz/human-body/the-line-of-action-or-strength.html

Other than that though this truly is a great start.

Thank-you for drawing me! You did a splendid job!