I suspect "my post it note" implies only one, which is hard to notice and hardly cheating, more of a kind of safety blanket. (you don't have to stress about forgetting what to say, which makes you less nervous and less likely to forget it in the first place)
A lot of people seem to write a stack of index cards with what they want to say, remember the first half of their talk, get stuck, and fidget around frantically trying to get back on track.
