Are you by chance referring to the 16 Meyers-Briggs types?
It's been claimed that it's less useful than it is popular: https://rationalwiki.org/wiki/Myers-Briggs_Type_Indicator
It's been claimed that it's less useful than it is popular: https://rationalwiki.org/wiki/Myers-Briggs_Type_Indicator
Knowing that someone is more neurotic than 99% of other people, would seem on surface be useful in predicting how they might react to new or novel situations.