Well, they do have to rest for the evening performance (especially if they have a demanding role), so a lot of them don't come out. Or if they do, sometimes they go out a side entrance so they can go get lunch and then come back quickly.
But there are some who will greet the fans for a few minutes after the matinee performances. I guess it's just the luck of the draw depending on how they feel that day?
"It's the little things; the details, that distinguish the Barbra Streisands from the Rosalyn Kinds."~Gilmore Girls~