It helped me because I had nothing, meaning I needed to take all the pre-reqs SOMEWHERE in order to first start applying. If your application would be in general weak, in just insufficient, a post-bacc program shows the admissions committees that you are willing to put in the work, and that you are dedicated to becoming a med student (and then a physician). You definitely do not need to do post bacc. You can always apply to schools, take some classes during your interview year, and if for some reason you don't get in, you can apply the following year.
Lots of the post-bacc programs are part of medical schools. Not that I'm endorsing a particular product or company, but simply because I own it........check out the Princeton Review Complete Book of Medical Schools. In the back is a list of post-bacc program my state. You can use that as a start.
Good luck
