One example: one college I know of had voluntary screening for depression and substance abuse. Students would have a short meeting (~10 minutes) with a counselor (someone who had a few hours' training in giving this kind of test), and the students answered questions about how they feel most of the time and how much they drink. It helped a few people realize they had a problem with these issues, but I don't know how effective it was overall. Some students had a problem but didn't realize it or were not interested in changing.

This book helped me, for example by showing what kind of praise different personalities usually want to hear, and by helping me understand the thoughts/goals of someone with a very different personality. It might or might not be a waste of time for others.