"It's better to sound right than to be right."
This is one of the best soundbites that Rex Martin threw my way during my studies with him. It gets right to the point.
In a performance, there is no such thing as one person being in tune and the other being out of tune.
Rather, they are out of tune.
If someone isn't balancing a chord right and you can do something about it by playing louder or softer (regardless of what dynamic is on the page), you are the obligated to adjust. Same goes for pitch and everything else.
This doesn't mean everyone should go around constantly adjusting to everything. That would quickly resemble one giant dog chasing its tail and never quite catching it.
But the definition of being a team player in a music is always being ready to do what sounds right rather than what is right.
It doesn't matter how many degrees you have, what gig you've got, or how many countries you've performed in. This goes for everybody.
Thanks, Mr. Martin, for making that crystal clear to me so many years ago.