Also from what I"m personally learning this application cycle, dont take too many gap years (in my case 3) if you want to go to a MD medical school. In my case I absolutely had to for personal problems.
The conundrum you can get yourself into is the following: Lets say you have a 3.7+ gpa (decent enough for MD). After college if you have a high gpa, doing a SMP or postbacc looks like a poor decision to adcoms. This is because if you do poorly in a SMP, then your hard earned 3.7+ is now essentially meaningless.
Furthermore, MPH's and many other graduate degrees have giant inflation in their grades and so rightfully so, MD adcoms do not pay much attention to how well you would do in a MPH or other relatively easy mode graduate degrees.
So bottom line.. if you take more than 2 gap years, they assume that you have forgotten how to read and write. Ok, not really, but you get my point.
Unfortunately this is my experience right now. Between a rock and a hard place.
So please if I can save you from this demoralizing situation, dont take that many gap years. I advise just one if you want, but thats it.