Totally School dependent in terms of who reads the app.
On Admissions Straight Talk, I've asked several adcoms how an application is processed. I don't remember even one saying that one reader reads responses to one prompt and another reads another prompt. From what I recall people read applications, not prompts. Schools vary on how many people read each app.
While it depends on the program how an application is generally reviewed or discussed, it is a logistical pain in the posterior. One thing is for sure, if such a process exists where an applicant's essays are individually reviewed, the program probably did not require the candidate to write a ton of secondary essays. On the other hand, that is how Kira Talent Assessments are scored (each faculty member reviews a number of respondents to a specific prompt, like an MMI).
