Do you think that after she sings [in a concert] maybe 3 or 4 songs her voice starts to sound I don't know wierd? I mean she IS my favorite singer.

NO.

I think her voice doesnt sound weird after a few song, because she trained herself. Like a lot of training to make sure it doesn't go off on the wrong beat. So my anwser is no. I think it doen't sound weird, not mader what.