For me, however, it just feels like chins, vertical pulls, or maybe even barbell curls should be mandatory vs an afterthought…the five should be six. I also like the idea of building strength with the body supported from above vs firmly planted on the ground or a bench. If I think of functional strength as so well represented from the other five, I also think about the ability to have stable strength and control while hanging; to be able to activate a lift applying shoulder stability, lat power, and bicep strength. Whether climbing through a window, scaling a rock face, or picking something up, such strength has overlap of course, but is still fundamentally different than the pulling and pressing movements of the current core movements. Lacking such a focus as a "first class" element of the core doctrine seems like a gap to me.