I think you should just map to the intensity of the song, and if the intensity doesn't allow for a map that's harder than a 4.21 star song, there's no point in overdoing it, it will just end up being an over-mapped mess.
However, if you feel like the song allows for a more intense map, yet you don't know how to make your map fit that intensity, I can definitely see your point. Sadly I can't help you though.