Almost everybody ... and I mean everybody who takes their craft seriously, has a vocal coach. It doesn't matter how big of a celebrity they are or how many Tonys they have on their shelf.
It's part of keeping up the stamina and making sure they aren't developing bad, irrevocable habits. It's no different than having a physical trainer. They need to stay in shape, and they need a second set of eyes (and ears) who can keep them on top of their game.
I'm sure Audra, Marin, Patti, Bernadette, Betty, Idina, Kristin, Kelli, etc. all have a vocal coach. No question.
They have acting teachers and coaches, too. And dancers take classes as well ... no matter how "big" their names are on a marquee.
"Jaws is the Citizen Kane of movies."
blocked: logan2, Diamonds3, Hamilton22