It occurs to me that the Art of Practicing may be wasted on a lot of classical singers. It is possible to be an opera singer and never practice by yourself. Ever. Coaches and accompanists can be relied on to pound it into us even if we come totally unprepared. Perhaps this is the problem. Why is it that the most expressive of all musical media, the human voice, is often the most monotonous in performance?
I couldn't play the piano worth shit, but I still worked out my performances alone at the keyboard. I sat alone with myself trying to figure out what made this piece tick. It is rather pathetic thinking about it. This included hours spent fracturing Das Lied von der Erde, among other things, a piece that I loved and wanted to feel in my fingers, to make my own, even though I never performed it. "O sieh wie ...." I wanted to feel those arching phrases in my own body.
If you are never alone with the music, how can you possibly find where it intersects your own soul?