>>47125139As she explained it once, UMG has a limited pool of tracks they let her select from, so she can't just pick her own producer and luck out like she did with teniwoha or Patterns. There's also a factor of time pressure: other songwriters have to pick from the same pool of tracks, so the "good" ones can all be taken away if she waits too long or hesitates.
And I'm not even sure if UMG lets her produce her own tracks like she did with Dead Beats and Live Again.