To answer the original question,if you absolutely need to void, it's a smart choice because not every medical school has a policy of taking the most recent, highest composite, or combination of highest subsections. Some schools take into consideration all scores within a certain time-range (usually 3 years). Also, even though a school's policy may be to take the highest score to combine the best subsections, they still see every score that is reported by AMCAS. Many schools have a "point" system such as GPA*10+MCAT to rank applicants, which is fairly objective. However if an applicant has an MCAT history of say 20, 20, 30 and an adcom can see that, it may stir up some negative feelings about the applicant even if not consciously done. That said, voiding should only be used in extenuating circumstances because people usually do better than they felt they did. Good reasons to void: nervous breakdown, sick, troubles with the testing center, not finishing many passages, etc.