Hello Opal, really sorry for the late response, hope that you're doing great and hopefully you're still having the same question on your mind, though i'm not quite sure which of the simplified forms you're asking, is it about gestural forms?
After taking a toll on your Artschool Journey, i realized that you're way better than me and i'm not sure my tips will do any help, but for gesture, i find that https://www.youtube.com/@lovelifedrawing
Lovelifedrawing really did a great job on how to simplify complicated forms such as the pelvis, and how to describe it's form direction in space.
For general stylize, i tried following Richard Powell's gestures and atm trying to learn to put Bridgman's Torso and Pelvis from Bridgman - Complete Guide to Drawing from Life, on the small simplified details such as how the Pelvis's Anterior iliac spine "outruding"? (must admit that i google'd the name) and also how the torso wraps around the belly.
I must say that my approach to gesture drawing is plain, it's like putting robot parts together, for robot parts, i meant for the parts that i like about gesture drawings from various artists.
Though i must say that only "feeling the flow" do really helps with gesture, the more anatomy on the gesture, the more clarification on "feeling the flow" it gets, this was what i extracted from Glenn Vilppu's gesture drawing process. He approached the gesture not that he tried to rush it, instead he tried to "feel the flow" with CIS curves first hand, and if there's time left, he would put some anatomical features to clarify the gesture.
Though from everything that i said, my gestures still not that great yet, feel free to put any feedbacks to them!
Really hope that you're not getting bored from reading this, English is not my first language so forgive me if i write anything wrong.
Thank you for passing by. I hope you have a great day. ^^