Done as part of a 30 minute class.
I really like the linework done on these sketches. Very clear, simple and cleanly executed.
now I don't really know what you want critique about, so I'll just write what I notice.(maybe you can write that on the canvas? I dunno)
I like the 30 second sketches. They are expressive of the gesture and very clearly drawn ( no unnecessary detail or construction lines, which I like)
I can also see that you know, or at least correctly recognize the anatomy in the model. I don't see any mistakes there ( except maybe some witch the 1min sketches due to time limt, but they don't really bother me, because they're not supposed to be finished lines)
So concluding I would say that you know how to see the model and also have the ability to draw what you see without problem.
What you could try now that you are in this position is to try to push the gesture more, to make it more expressive than an accurate representation of the model and with that try to get at the essence of the pose. Trying to exaggerate the pose will help you understand what influences body language and how to modify the pose of the model to express what you want it to express ( instead of what you saw the model do ). With that I for example that if the model looks very clumsy to you, that you try to exagerate that feeling while drawing the pose. And while drawing to think about the clumsyness of the character and maybe alter the angles of the arms stronger so they look more wiggly or change the balance of the legs and feet so he looks more unstable. Things like that.
In exagerating you can also look at the "line of action" or "squash and strech" which are things disney animators pay a lot of attention to ( maybe something to read about if you're interested? they also talk alot about poses )
Finally I'll also say something about the rendering on the 5 and 10 minute poses. I'm not sure what your intent was with the rendering. Did you just do it because you had more time? Did you try to figure out rendering? Did you try to capture the mood? How they are now they feel like an exercise at seeing the Light on the model.( that's perfectly fine too )
The rendering is actually pretty well done. I can see the highlights, shadows and mid tones cleary separated and they make sense as a light source. The shapes they form are also pretty, as they are simple and interesting shapes.
What I suggest doing is try to push the froms of the body more using the hatching in the shadows. You did this well with the Arms and shoulder in the 10 minute pose because the hatching supports the 3dimensionality of the forms. But the legs, especially her left bent leg look very flat because the hatching is very straight.
But if you really want to get into rendering maybe you can do a value study instead of using hatching. I think it helps more (than with hatching) also with how the forms change surface direction (like with a sphere or cylinder).
I hope some of this helps you improve on your own :)