Re emotion I have the same emotion every time I sing the song and if I am in a studio usually do it in one take obviously after sample balances etc have been sorted. If I do a second take it is usually just as good/bad as the first take. Messing up lines is normally the main cause for a second take. Studio time is expensive and you sometimes wonder where it went.
Before going into a studio you should know and have practiced the material and have worked out how much time to spend on each part of the process. It is professional and saves time money and heartache. It also helps you to work to a schedule.
The best recording session singers are not always the best vocalists. They are the ones who can do a good job in the time and budget given.

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