I suggest more gesture drawing, more speed and scribbling, especially in the 30 second and 1 min warm up pieces. By focusing on just the outline your pieces can be rigid. Also try out blind drawing (where you only look at the reference and not your own piece).
One specific part is in your last piece you see that you fill in the shorts and top. Imo this kind of "left brain" practice (Dr. Edwards) can be bad because it means you thought "this shape represents the shorts, let me just fill it in". But if you forget symbols and objects, and go down to the level of just shades, lines, curves, I bet there are actually many curves and forms hidden in the shorts. Her buttocks, hips, etc.
My suggestion would be to spend more time in the 5-10min range atm. I think you are still a bit inexperienced, so won't benefit too much at this stage from the shorter timeframes like 30 secs. I think it is too short of a timeframe to make good anatomical observations as a beginner.
I believe it is much more valuable at this stage to gain a better understanding of the human body through keen observation in longer time sessions. Then consider revisiting the shorter sessions as a constant staple in your drawing routine further down the track, when you are more comfortable in your knowledge of the human body's shapes.
Hi, I'm still a newbie myself, however, allow me to give you some crituque:
I've pored over your three images, I think structurally they look impressive for a beginner. However, you are focusing far too much on contours and shapes in your gestures and less time on the actual GESTURE of the figure. That is to say, you are mainly concerned with the drawing looking like a completed image rather than worrying about how you're translating movement on page.
You can start by observing your lines: they lack confidence. I can see by your strokes that you are more afraid of messing up than making mistakes, and that's normal. Try to draw more confidently by practicing ghosting your lines first on a separate paper. This will teach you a bit about line confidence.
Next, your boxy figures are good, however, you're relying on them too much. Scribble, loosen up a bit and draw what you see the gesture doing and not what it is. I suggest starting off by doing simple lines.