At large law firms, unless you’re interviewing for a small practice group, nobody’s losing sleep over whether you’ll fit in. They’ll take you so long as you’re smart, willing to work crazy hours, and not obviously a jerk. (Although if you’re a rainmaker jerk, they can’t seem to roll out the red carpet to the corner office quickly enough.)
You’ll tend hear the concern about the “right fit” voiced more often for in-house than Biglaw job openings. When you interview for an in-house position, your technical and substantive abilities certainly need to pass the bar (every possible pun intended). But after that, there’s a broad and maddeningly vague analysis regarding how good a “fit” you are….