Toasted

Over my breakfast this morning I was thinking about toaster designs and how most of the time I only want to toast one piece of bread.  If there was a button somewhere on the toaster that switched off the elements in one of the compartments, would it save power? I think so, which could potentially make a huge energy saving over the whole country. It would certainly prolong the life of the toaster.  The button could be highly visual and tactile, not needing an L.E.D indicator and would cost very little for manufacturers to add.