I am a guy who have gone through med school, residency and currently going through fellowship application. Just take my word, apply to as many program as broad as you can afford.
I thought I was hot **** applying to fellowship with 250+ board score, multiple big presentations and big journal pubs, yet I gotten rejected from 50 percent of my initial 20 applications (which was strictly the list of top 20 programs concentrated in the coasts) While people are sitting pretty with more than enough interviews to go from the get go, I had to add another wave of application (down to a 20 percent yield, no love from "safey program as good stat plus late application screams panic).
Now I have a pretty good list (as in I will be very happy dropping up to #10), but I still have occasional angst about not interviewing at certain programs (gf would remind me that I didn't apply there...)
You can always decline interviews, but application fees are much cheaper than having to add second rounds and go on last minute interviews when others drop...
Big lesson learned:
Apply to as many as you can. I applied to 30% less programs than the average IR fellowship applicant, which seemed smart at the time, and probably will be smart later on, but emotions are in the play and believe me, you don't want to feel like you aren't pulling as many interviews as the next guy.
Apply broadly and concentrate on a tier base on your stats. It's hard to know how competitive you are the further you go (say the coastal programs interview 20 people's each, if you aren't within the top 20 applicants in the country suddenly you are SOL)
And lastly, go on as many interviews as you can afford.
Hopefully you only do this once.