I'd say you are using too many lines, especially in the 30 second and 1 minute gestures. You should be trying to capture the essence of the pose with the least amount of lines possible. Also for gesture you need to use long flowing lines. The ones I see here are short and choppy, even in your longer drawings. I feel like you are trying to draw the entire figure in 30 seconds, which isn't gesture. In the longer poses you should start with a gesture of the pose and then build on top of it.
For figure drawings, less is more. Try focussing, not so much on the details (hair, muslce tone, fat) but more on the expression and movement of the subject. Try drawing lines or shapes that symbolize parts of the body.
Something I found that helped me with understanding this stradegy was drawing a piece of paper. First, flat on a table (so just a square) then, imagine its a face, facing the right or left, so with curved lines at the top and bottom. Try using this site's face expression drawing tool but only draw the piece of paper. Really interesting results :-)
You're drawings are very good, you definitely understand drawing techniques and excecute them well.