Thinking about my previous post on getting along with people in a show, I ought to mention the other points of view.
My mantra tends to be, "I'm in this for the design." So I judge decisions against that, asking: is this decision/action/behavior/hot-tempered outburst... better artistically, truer to the text, or better for the show? ("Better" is filtered through the playwright's, director's, and team's goals, not just personal whim.) You might call this the Project Oriented camp.
You can make a good case for a Service Oriented point of view, where the designer serves the show, of course, but primarily serves the director. (Directors like this!) Many theater schools seem to teach this approach. Or the designer might be yoked to the producers - a resident designer maybe. Don't be fooled, service-first designers often design wonderfully well - they have to, to get and keep the gig.
Ego Oriented is where some designers pitch their tents. This becomes slowly obvious in their work: their sets express a strong design idea - often brilliantly! - but are ungenerous in supporting the show itself, unhelpful to actors, director's, or other designers' work or to producers' and builders' difficulties.
Much of this difference in approach may be temperament, not choice.
My own first loyalty tends to be to the Project, though I believe in service, teamwork, and pragmatism. Service orientation can feel acolyte-like or have career advantages: you might bond with a director and ride their coattails around the regional theater circuit. (Assuming enough talent - always assuming talent and hard work.) The Ego thing... I'm biased against (ego hurts the show and is obnoxious), but egotistical designers succeed. Look at Frank Lloyd Wright! Some designers think they need to be divas, since the gullible equate ego with talent.
So pick a camp - if you can.