Ah, but you still have to let go of the Shift key, your left hand is still positioned low down on the keyboard from pressing the | key, and pressing two different keys is still slower than pressing the same key twice! Hah! >:->
Of course, on a French keyboard, you don't press shift to get the $ but you have to shift to get the 1, so I'm not sure which would be "most efficient". This requires further dilligent study.