I had 5 interviews with 8 people over the course of a month. It was not super convenient to schedule and seemed redundant sometimes but the interviewers themselves were personable and professional.

I had a day of interviews, about five or six all told, each lasting perhaps 30 minutes. I didn't do as much preparation as I should have. The managers I interviewed with are all gone now so I suspect my experience wouldn't necessarily help someone interviewing there now. One thing that likely hasn't changed is that you will meet with a number of people during the interview. NPR loves its meetings.