SEPARATE REHEARSING TECHNICALLY FROM REHEARSING PERFORMANCE COMMUNICATION.

You need to separate rehearsing technically from rehearsing performance communication. You should rehearse technically until you don't have to think, then completely go on stage in your mind and perform to the unseen other who will be listening to your CD. You have to make this person real for yourself  much like an actor going into character.

DO NOT practice performance much. Just when you're ready, once or twice at the most, a day. Only practice the drills of technically performing the song.

It's a mind thing, and a set-place thing. When you perform, the act won't be authentic without the listener involved. THE CONTROL ROOM DOESN"T COUNT.
Sing to the beings who will be listening to your CD. But then once you've performed, it can't feel authentic again for a while, because after all, the listener's already heard it, and for goodness sakes you don't want to bore them. And think about it, once someone performs in an olympic event, does anyone ask them to repeat that all-out performance again that same day??? Not and live to tell about it.

And I mean not only in live performance, but in seeking that studio master vocal as well. If you have to sing it too many times, you need to park it and come back another day. Even making an actor do a scene too many times takes the life right out of it as they lose perspective and inhibition creeps in.