I suspect she has some ace in the back pocket like a great life story, a major recommendation, or a very notable achievement. She strikes me as the type of person who would listen to her premed adviser, and if so, they probably signed off on her decision. Even though she only got into one school, that invite list is impressive. My take: she is a solid candidate in a non-boilerplate kind of way.
I recommend that all potential applicants do everything in their power to apply and get into medical school on one application cycle. I know you all are trying, but simply put, boilerplate candidates cannot afford to apply to just 17 schools.
Disclosure: I applied to 17 schools, got five interviews, one acceptance, one rejection, and withdrew from two places. I got accepted to a higher ranked school than hers, but my invite list was not as impressive as hers. I applied to 17 schools because I was just willing to walk away if I didn't get in on the first cycle.
Good luck everybody. If you don't get in, it may be a blessing in disguise.