Consistency is important; so is evolution.
Consistency is the hallmark of a professional. I can reliably perform this piece every single time, regardless of circumstances.
An ensemble should strive for consistency. Once a bar has been reached, it must be reached every subsequent time. Once a standard is set, it’s there for good.
But also…a piece shouldn’t be the same every time. The weather, the acoustics, who’s present or absent from the ensemble, the audience…all of these should affect the performance. And if you aren’t balancing consistency with a commitment to letting your repertoire breathe and evolve with the moment, then you are doing the music a subtle but important disservice.