Do not underestimate the importance of "fit" and showing it in your secondary. After having successfully gone through the cycle, I feel like there is more legitimacy to the whole process than I initially thought. I say this because, even though n=1, after applying and being complete at fifteen schools, there were two specific schools that I felt were a great fit. Somehow, among thousands of applications, those exact two schools were the only ones I interviewed at.
Considering there are so many applications to be reviewed, it felt like a real possibility that the primary is evaluated fairly quickly to assess for baseline threshold metrics, extracurricular activities, and personal statement and as long as the primary baseline review looks okay, the secondary is reviewed in detail to check for individual fit with the program; which at that point, if you are a clear fit, you receive an interview. I have no clue if this is true, but I definitely do not think it is coincidental that I received interviews at the exact programs I felt were a clear fit. The secondary essays are extremely important, do not rush them. Do your research on the programs and make sure you are able to show with words how you are a great fit for each specific program you are interested in.
Also, do not apply DO if you would not be happy attending a DO school if you do not get into an MD program. If you search the forums, you will see there are a lot of people who applied DO and got accepted, but were not accepted to MD (which was what they really desired) and are now faced with a very difficult decision that will stick with them for their entire career. Take the long view, if MD is what you desire (for whatever reasons), and you know DO is not what you want to do, then only apply MD but understand it is very competitive and might take a few cycles to get admitted. Good luck!
