Timeline for AMC, PSAT, SAT, etc

15 minutes of test prep did seem to be well into the normal range back when I was in high school. But it now seems to be an extreme outlier on the low end.

Also, the typical test prep for Achievement tests (SAT subject tests, before their recent discontinuation) and AP tests then was taking the course. I.e. no additional prep for these tests. But that seems unusual on these forums in recent years.