I'm interviewing for residency right now and it's a bizarre process. I'm applying into neurosurgery and surprise! it is a 7 year, "88" hours a week, 5am to 8pm on an easy day, work your ass off residency. Turns out people want neurosurgeons to train kinda hard like.
So going through this interview process is a strange trip. On the one hand, most good applicants get a program in their top 3 choices. That's pretty comforting. In fact, by far the most common scenario is to get your number 1 choice. And more than that, most people like their home institution and their home institution has interviewed them for the 4 years of med school (particularly in neurosurgery where people start from day 1 walking around introducing themselves as, "Hi, I'm JohnI'mgoingtobeaneurosurgeon, what's your name?"), so it's sort of clear that it's a mutually beneficial situation and a bit of a lock.
However, there are political games galore, lying, applied game theory, and tons of horror stories of the "locks" at Home Institution University ending up at Third Best State School in the Region University. So everyone gets very nervous, no matter how good an applicant and develops a self destructive habit like alcohol abuse or watching Whitney.
A common question at this point is, "well what's wrong with Third Best State School in the Region University, won't you still be a neurosurgeon". Yes, and likely a well trained one. Still, 7 years, working that hard with 7 to 21 other people (most programs take 1-3 residents a year) is just not a flippant choice. It's like trying to pick the best prison for you. Which penitentiary has the coolest inmates? Who's the best Warden? Where do they give you the most time for arts and crafts, but still enough time to read? How much outdoors time do you really get? You can't switch residencies (or rarely) and you can't speed it up. At the end of the day, we will all be rehabilitated and ready to re-enter society, but you still want the best prison possible.
Let the games begin!