Would you rather read a letter written to you and 20 of your friends? Or, would you rather read a letter written directly to you? Most would choose the letter written directly to them because of the personal nature of the correspondence. The Common Application Personal Statement is basically the former. It goes to every college and thus can feel less than “personal.” Whereas the supplemental essay is a response to a question the university specifically wanted to ask its applicants. It is deeply “personal” in that it provides the opportunity to explain how and why the student can both grow and provide value to the university community.
Sometimes students spend SO much time on the personal statement that by the time they get to supplement number 7 they are tired. Resist the urge to slack off on the supplement. These essays are very important in highly selective admissions.