From a comment on YouTube attached to Victoria's performance of "Mi chiamano Mimi":
"Elisabeth Schwarzkopf wrote, when she saw [Victoria] de los Angeles debut at Covent Garden as Mimi in 1950, that she cried, because of de los Angeles perfection in the part and because she realised she would never reach such levels in the role and withdrew it from her repertoire."
Elisabeth achieved immortality by carefully selecting the roles she portrayed. She focused on those roles in which she achieved perfection, those roles in which she was the greatest of her era, and it was not many.
I think this is a useful model only for those who aspire to greatness, as she certainly did. Know thyself.