I play bass in churches. I get to work with a lot of worship leaders. When we get to the church, we have a couple hours to rehearse stuff - sometimes stuff we've never played before, often with people I haven't played with before, and get things to the level where we can (hopefully) inspire an audience. None of us have the luxury of having egos drive our decisions. I work a lot before I get there to understand the songs, and work out parts I think that leader will like - sometimes it's pretty much what's on the record, sometimes it's got a few new twists in there. I always adpat my parts somewhat in real time - if the feel from the drummer is different, what I play is likely to change to work with that.
If the leader isn't feeling something, I don't defend the part I came in with; I ask what they'd like. I'm not paid to do what they want, but it's part of being a good team player to be flexible and get behind that person's vision as much as I can - we simply don't have time to have a bunch of discussions about everything. It doesn't happen too often, but when it does, it's my job to wrap my head around and own the part I'm asked to play. If someone wants a parade of quarter notes, I'll give them the best damn quarter note parade I can muster.
I realize not every band works this way, but in general, I think adopting a "lower ego" position is a good approach. That means both that we shouldn't be quite so proud of our parts, but also that we shouldn't tell others how things "should" be. We should offer up ideas, and try them out together - keep what works, ditch what doesn't.