Hey Khas drake, one thing to think about is what your end goal is with the site, is it an overall understanding of the human body, just to get quicer gestures down, or to really understand the muscles and the body completely, if it's just for gestures or a general understanding, you might want to try loosening up your 30 second and one minute drawings. It can feel safe to syay with the construction method but in 30 seconds there isn't really much time to get past the basic layout and you don't get as much out of it as in the 5 minute+ ones. maybe try startign the sessions without any construction, or jsut a gesture line and then pick a part of the body, I like shoulders a lot because it leads into the arm, the head and the torso to give you good proportional sense for the rest but really its whatever in that specific pose you think can guide you, and it leads to bringing a lot more life into your quick poses which eventually helps you with the longer ones too and can keep things from getting too stiff.
As for working on volume and making thigns feel more substantial, understanding the 3d forms that make up the body is important for whatever your end goal is and some great teacehrs are moderndayjames and krenz for that, james has a lot of stuff on youtube, particularly this one for human forms but a lot of other good content as well and they both have really cheap gumroads with a lot more helpful information on form and perspective here https://gumroad.com/krenzcushart and here https://gumroad.com/moderndayjames?sort=page_layout#BUOKs , hope some of this helps, and good luck!
