Debussy, Mahler, Strauss, Sibelius, Bartók
This is true. Sometimes one-off performances can be rather special and here I'm thinking about Salonen's recording of 3rd. I haven't heard this recording in ages, but I remember being rather impressed with it. I don't really think of Salonen as a Mahler conductor (besides the 3rd, he's recorded the 4th, 6th and 9th).What I value a lot are the performances which are not part of any cycle ... Hannigan's 4th, Barshai's 5th, Harding's 10th etc.