You shall therefore lay up these words of mine in your heart and in your soul; and you shall bind them as a sign upon your hand, and they shall be as frontlets between your eyes. And you shall teach them to your children, talking of them when you are sitting in your house, and when you are walking by the way, and when you lie down, and when you rise. And you shall write them upon the doorposts of your house and upon your gates, that your days and the days of your children may be multiplied in the land which the LORD swore to your fathers to give them, as long as the heavens are above the earth.
By the time you get to the "Twelve Drummers Drumming" in the Twelve Days of Christmas you pretty much feel like you know this song. It has been (ahem) drummed into you. Repetition has a way of doing that. It's why we teach our children to parrot "Please" and "Thank you." Not because we are raising our children to be parrots, but because we are raising them to have civilization be second nature to them. It was the same in ancient Israel. You hammer away at the basic truths of the covenant God made with your people so that your children would have it encoded in their breath and bone and the faith would not be a one-generation wonder but a heritage for all time. For the same reason, the Church drums into us the Twelve points of the Creed so that it will be second nature to us and so that, when we are gone, our children will carry the torch of faith to their children.