A practical question: I have now read a few times that to get a PhD position in the US you need 3 reference letters. I assume most people apply for more than one position, so you need those 3 letters for every position. Also, there are a lot of applicants.
So how does one get a professor to write more than one letter? If I apply for say, 5 positions, I would need 15 different letters, 5 per person if I am always referring to the same persons, even if not probably more than one letter per person---and I am probably not that person's only student who wants letters.
I cannot possibly imagine professors in Europe going along with this (which is why it is becoming common here to just give the address of the referee, not send in a complete letter), so how is it in the US?
Do US students only apply for one or two positions and simply abandon the thought of grad school if they do not get it, or do they really get their professors to write that many letters?