Question is: anyone else here submitting supplements? Four people in my class are applying to Stanford and all of us are submitting music supplements, I’m also submitting an art one. If this common? Maybe it’s just because the four of us know each other personally and influenced each other to submit supplements?
Depends on (a) what the supplement is (i.e., literature, tuba, dance, etc.), and (b) how good you are.
You should submit a supplement only if it is integral to your application and is expected to be well-received by faculty members. Also remember that, as an example, far more piano performance supplements are submitted than music composition supplements; therefore, it is harder to “stand-out” as a pianist than it is as a composer.