[rhizome]

A top school is a good signal for how much time someone spent studying in high school

Assuming all high schools are the same.

[techman9]

And the classes the student took. And the environment a student grew up in. And how much support the student received. And any one of about a million other things.

There are virtually an infinite number of variables that contribute to university admission and it's extremely reductive to suggest that it's purely a function of the amount of time a student spent studying in high school.