Interesting, this is likely a new topic so as to not distract from this beautiful, confusingly-used board.
I’ve always centred the boot over the middle of the binding, then angle bindings until perpendicular over the edges. But in almost no case will I get directly over both toe/heel, so I typically adjust the bindings slightly toe/heel (along with stance angle) to centre the boot over the board edges.
But my boots are always centred on the binding. It sounds like everyone else uses the slots for adjusting stance width, but the binding is always placed on the middle of the board and you offset the boot on the binding to get perpendicular over the edges?