My reasoning was, that they are attached to the bar just like on the flats, but at a 90deg angle. Also, the diameter of drop bars is a few cm larger than flats, (I did not know that), so you cannot put it over the bar (which is what I orriginally intended to do). However, it is surprisingly easy to shift. If i did it again, I would probably put them in the same place, although if I had money, I would get bar end shifters which are only $60.
Cheers