i think, probably, the backs of peoples heads? i went through gcse year quite recently and in exams it would be constantly drawings of people from behind, and basketball hoops. i also draw people in-situ if im sitting around bored somewhere ,esp festivals - thats usually from behind, otherwise its awkward. either way, its great for learning to get shit down fast and tighten up anatomy and clothing & hair details.
when drawing from my mind, though, ig cath from my comic would be my go-to because of her appealing design
ive also drawn a TON of alphona style kamala khan. got a whole sketchbook FILLED with transcriptions from v1 of ms marvel