Students that my schools reject are generally in two categories. The first category are those who are just not competitive enough. This means that by evidence on AMCAS, they would not be able to get through a challenging medical school curriculum. These students are usually not invited for interview. This category represents a majority of student who are rejected without interview.
The second category are students who have interviewed who just will not fit in with the class or the medical school. As accepted students indicate that they will be attending, the class starts to take shape. Some students will interview with very poor social and communication skills that they would not be able to get though four years of medical school let alone get along with other human beings. To successfully navigate through medical school, a person has to have more than just grades and MCAT scores. Every year, we receive thousands of applications for a little over 100 seats.
The last category of students are those that would be placed on a wait list. If a slot opens, they will be offered admissions. If not, then they would not get in that year. These are the folks that should definitely reapply.
MDapplicants is self-reported data. If you are interested in a particular school, you should ask the admissions office why they reject students as opposed to looking at self-reported data. While many people are honest on MDApps, many people are not.
If you are a strong applicant (well above undergraduate GPA averages and MCAT averages) then you may be able to apply to less schools but most applicants today apply to a minimum of 10 to 15 schools. Start with your state schools and go from there using the latest version of the MSAR as a guide to where you rank in terms of competitiveness for the schools that you apply to.