Sorcha, When I first started trying to learn the pipes I thought as you but, I soon found out that that wasn't so. In Some pipe schools you spend all your time in the beginning learning the various doublings & such. There are even hard core folks who say you have to play all the grace notes or you are just a fake piper. I don't clame to be anything but a begining piper but I play a lot of other instruments compently at the very least so this line of thought was & is foreign to me. But you are right there are only nine notes to work with so the doublings do often make up for the lack of notes