Probably the biggest thing you can do to improve is start marking which ones you think are the best.
See, the observation you do during the 30s and 2m and 1m poses sets you up to do better during the longer poses. And if you don’t pay attention to what works, it’s a bit hard to repeat it.
I can definitely recognize the pose for your 10m picture, so you’re doing some things right. But I don’t think that’s the best you can possibly do in 10 minutes either, it’s very stiff feeling compared to your shorter poses, and very spare and outline focused.
I think the main thing is to don't be afraid of drawing more lines. I would look into contour drawings this will improve your longer timed drawings. Don't be afraid of shading as well, either with cross hatching or soft.
Here is some general 5 mins and 8 mins (had to cut it short due to outside interference)
I did try to color code a little bit with the 5 minutes. Light blue is 1minute, 2nd is dark blue, 3rd was light pink, 4th and 5th is dark red
I would take advantage of the extra time that 2 minutes gives you to sketch out a frame and start thinking of visually measuring your figures as you sketch them. It looks like the proportions are a little unnatural in some of these which I totally get with 30 seconds since you're just getting down the general shape, but with 2 minutes you can start to pay more attention to making the poses more believable or structurally sound. It gives you a better baseline for when you get to those 5-10 minute poses!