Usually when someone is struggling to get 20s despite having studied for the MCAT for several months it means that they might not have had a good command of the material that is being tested. A lot of people take the MCAT and some people are just better test takers than others, but even those who aren't so good with these computer-based tests usually score in the upper-20s low-30s if they know the material down pat.
I don't know what your situation is, but if you studied adequately (several hours per day) for 3 months for the MCAT, have taken several of the practice exams, and are still struggling with the exam, you might want to consider taking more bio/physics/chem classes and changing your study habits. Consider putting off taking the MCAT until you've learned all the material, completed your pre-requisite classes, and feel comfortable with taking computer-based multi-choice exams. I think it's usually a bad idea to take the MCAT unless you know the material well since a bad score can count against you.
I definitely agree with the above. You need to get the term "MCAT's" out of your vocabulary because this is one test Medical College Admissions Test (MCAT) that you take one time.
Problems with the MCAT are usually along the line of inadequate knowledge base or inadequate test-taking skills base or some combination of both. Both of these problems can be overcome with study and practice. Because the MCAT does not test in the same "regurgitational" manner as most undergraduate coursework, many students have a great deal of difficulty scoring well on this test in spite of doing well in college coursework.
The MCAT review courses may be an option if you are having difficultly with knowledge base. They present the knowledge in a manner where everything is essentially in one place for you. They also provide plenty of test-taking practice both to assess whether or not you are mastering the materials and to hone your test-takings skills too.
The review courses are expensive but well worth the price if you need their services. Before you invest the time and money, you should do a thorough investigation of what they offer and how they offer it so that you take the course that best meets your needs.
In addition, there are retired MCAT exams that are close to what is on the actual test. Purchasing a couple of these and taking them under testing conditions is a good way to get your testing mechanical skills up to par. There are several of these tests (plus one that is free) available from the AAMC website.
As stated above, do NOT take the MCAT until you are comfortably scoring well above average on the practice tests. The MCAT exam is not to be taken for practice. More than one retake starts to greatly count against you if the scores are mediocre. You can make the case for one poor performance but two or three becomes a pattern that you do not wish to display.
Rather than worry about what others are able to score or not score, get your problems solved and retake only when
you can score competitively. This exam is a critical part of the process of becoming a physician. A high GPA will not "overcome" a poor MCAT and a high MCAT will not overcome a poor undergraduate GPA. You need both so make both your goal.