You're doing well -- nice work practicing gestural lines that aren't overly contour-y or anatomical. I'll recommend a few things. You can look at some of my sketches a few posts below yours to decide if you want to take my advice. I have found that figuring out whose advice to take and whose to avoid is a big part of the battle in learning to draw. For your thirty second poses, you don't have to do this all the time, but I would recommend practicing drawing limbs and even bodies with a single, gestural line. I spent a lot of time rapidly drawing gestural sketches with bodies and limbs that were full enclosed, and while that's all well and good, I think working on single, flowing lines is good practice to make your sketches more gestural and expressive. Secondly, take a couple seconds to analyze each pose for the line of action -- ideally a single line that runs through the entire pose. For example, the bottom pose on the left image of a figure reclining with the arms outstretched behind them -- you could have drawn a single C-curve from the neck down and curving to the left all the way to the heel of the outstretched leg. The bottom left figure on the second page, the figure with one arm over their stomach and one above their head, you could have extended that line of the neck down all the way to the figure's right (our left) knee. You were almost there, but you drew two lines instead. It's okay sometimes to discard one of your trusty, go-to rhythms to accommodate a fluid line of action. Most importantly, keep it up. You'll be glad you did.

These are very nice! You should post more of these as you go. I’d love to follow your progress.

These are fabulous! I don't think they look weak at all. It seems like you are using your artistic sensibilities and drawing what you want to see, which is great for gesture. I really enjoy all of them but I particularly like what you did for the 1 and 2 minute poses. Drawing from imagination takes time and you're obviously putting in the work -- keep it up along with studying anatomy and you'll get there!

Two weeks later, here's where I'm at (30 second, 1 minute, and 2 minute poses). I tend to feel like my sketches are regressing, but hopefully they aren't! I can "see through" the contours to the spirit of a gesture pretty well by now, but I have a very hard time getting myself to modify poses under pressure the way that Stan and other skilled artists do in their demos.