The above response really does sum it all up...

I'll just add in my 2 cents... If vocals were recorded like live albums then most new albums would only take 2 to 3 hours to record... Not weeks, months, or even years... Albums are made just like Movies where they collect a bunch of takes/tracks and literally copy and past them all together seamlessly. Let a little common sense prevail here but the more solid the artist, the quicker the vocals could be recorded... That's why the Blaze album was complete start to finish is a month... And the end result is a vocal masterpiece.

Of the choice of 2, it might be easier for an artist to start off in a higher key verses switching from lower to higher... Also wording could play a role in hitting certain notes too.. They could have an artist sing totally different lyrics or just gibberish to get to the note and then once that get it, delete everything else behind it...

If you ever listen to one of those vocal only tracks, they sounds much different with all the music stripped away. It's even possible to go back into the vault and pull out a vocal from a totally different song, paste it into a new song, overlap it with new music and you would never even know...

I remember a few years back there were talks of creating a new Elvis song. As long as they select lyrics in the right keys, it's like playing a piano...

There are also little thing like speed changes too. WDR