Applying to more than 20 schools is wasting your time and money and wasting the time of those people who will handle your application. It is far better to apply to fewer schools and do a good job on each secondary than to do a half-ass job and make mistakes (I've even seen an essay where the applicant expressed great interest in attending a different med school -- I guess the find and replace function didn't work as it should have. )
If your application is good, 50 applications will exhaust you and your bank account. You will feel obligated to attend every interview until you have an offer (mid-October at the earliest) and that will drain your bank account (or run up a credit card bill). It will also have you sounding rehearsed far sooner in the season than other applicants (that isn't good as it comes off as insincere). You will also be stressing out about not hearing from some schools until later in the season (you are going to be "late" with the supplementals at some schools just because you will have a backlog of them in the weeks after your AMCAS goes in.)
There aren't 50 medical schools in the country that are a good fit for you. Look at your personal characteristics (state residence, academic performance, interests outside of clinical medicine such as research, community service, global health, and recreational activities) and your lifestyle preferences (e.g. do you love or hate cities of > 1 million, want to be close to an area with others who share your ethnicity, religion or other characteristics)... if you are honest with yourself and do your home work you can strike many schools off your list as those you wouldn't attend even if offered admission. (We see this along with the pussywillows every spring, "I got one offer of admission but I don't like the school, does it look bad to decline the offer and reapply in the next cycle?")
Buy the MSAR. Pour over it with a packet of post-it notes in one hand and a highlighter in the other. I guarantee you will come up with a solid list of 20 schools and if you are very well prepared you may actually walk away with 10 interview invites and 5 offers. If you aren't as strong but you target your applications well , you'll get the one offer you need and it will be a school where you'll be happy to attend.