In my case, I do not have and never had.
Funny thing, gophert, that every time I asked why could I need one, the prevalent answer, even from account officers in the bank, was "to take advantage of the promotions showing up at any moment in so many places" ¿?
My ignorance on the subject was (is) so complete that when my secretary started to work with me so many years ago, she was using intensively, minimal payments; I believed she was a financial genius!! Go figure.
Sorry for the digression.