WM bags are "adjustable" in a small way... In the BADGER model, since the down is contained in continuous baffles, the down can be pushed on top of you if you are very cold and off to the side or under you if you are hot. I use this feature for each night to be sure I match the temp with my bag & down to get a good combination. It's nice because my 20*F bag will serve all my needs throughout the year here in the south. The full zipper makes a nice vent too!
I always forget and make it more complicated than it needs to be...it's just walking.