I was thinking the exact same thing. To attain the level of experience needed to successfully interpret musical keys to the dream world perfectly would mean countless of hours of practice in real life. In actuality, defeating the purpose of refining ability in an LD in the first place.

Also, as MrTransitory said, LDing inherently relies on expectation. This would unmistakably affect your progression of skill and obviously your sense of achievement.

Reading is already a pain for most people, the maths you do in the dream would probably be questionable. Although, I've heard of people who have calculated mathematical problems in their dreams and then awoken to find that their 'dream answer' was correct. Anyone had any experience with this?