There's a lot of rep out there that takes HOURS to learn, even for experienced pianists. Pianists on Facebook (People for the Ethical Treatment of Accompanists) kicked the idea around in a 'Repertoire Difficulty Level' discussion, naming repertoire from their own experience. I pulled together a list, offering two categories: pieces originally written for piano and orchestral reductions.*
If nothing else, pianists should:
Double check before saying yes to Hindemith or any saxophone repertoire.
Originally for piano and [fill in the blank]
Casterede Sonatine, trombone and piano
Creston Saxophone Sonata
Desenclos Prelude Cadence and Finale, sax and piano
Jolivet Chant de Linos, flute and piano
Franck Violin Sonata
Heiden Saxophone Sonata
Ravel Tzigane, violin and piano
Schubert Variations On 'Trockne Blumen', flute and piano
Strauss Violin Sonata
Šulek Vox Gabrieli, trombone and piano
Weber Duo Concertante, clarinet and piano
Copland Clarinet Concerto
Dvorak Cello Concerto
Strauss 2nd horn concerto
Ibert Concertino for Sax
Walton Viola Concerto
Vocal lit should have it's own space . . . I may have to do that next.
*Orchestral reductions get their own category because playing them calls for the ability to make an orchestral sound, in addition to the ability to read (and to discern what to bring out/leave out/etc).