Why do you limit karaoke books to 5 per account? Seems like a horribly artificial limit, to me.
Have you heard of database NORMALIZATION? If you lifted the limit *completely* and normalized the DB, you'd have a system now and for the future. As it is, you are boxing yourself in a corner because of your perception of current devices, without thinking about the future when surely device screens are going to be larger and/or more flexible. Think iPad, and its kin, with adjustable screen resolutions with a pinch of the fingers.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.