@Chri
Why there are not "temporary" violet rectangular volume ?
Because you make a direct PushPull on the piece ?
Because sometime, maybe there will be more easy to put this temporary box and "pushpull" it than try to find a face to extrude! :)
(no need to orbit in complex position)

And for the Red Blue Yellow : it's allways the same or depending of the "Thickness" of the piece?
(have they same thickness ? )
There is no measure of the thickness of the principal piece! :)