In my experience, they are many things. To me, lines (too many or too few) do not necessarily matter because they are not "finished" pieces, merely "warm ups" or studies, also because from what I can gather from my recent readings upon gestures is that you're trying to capture the motion and "essence" of the figure, not necessarily the figure itself.
However, from seeing other people's gestures on this site, there are many definitions and types. But maybe they are not traditional gestures? I see a lot of contour lines when people say they're doing "gestures". I do this too, but on my longer studies (5mins+).
I am still trying to get down "gesture" drawing, and trying to draw the motion and activity of the figure. It's seemingly difficult for me. Haha! Also, trying to figure out the proper placement and posture for drawing on a digital tablet for optimum arm movement. Any suggestions on this?
Thank you so much for stopping by! And leaving some ideas! I will implementing your idea and see if it works out for me!