This is something that Mike Mushok quoted; "Learn all the theory you can, and then forget it."
I always thought that that ment once you know your theory, it becomes so easy, almost second nature, almost as if you know it by heart in the back of your mind, almost forgotten. Knowing your theory this well makes it easyer to write songs properly, I suppose. Thats just my interpretation of what he said. Give it a little thought.