The Role of Intra-Subject Variability in Personality Psychology

Personality is the combination of all things that sets a person apart from other people, right? And that would be unique per definition. So I'm not sure I agree with the premise that people mostly think in terms of intra-individual variability or at least they might be thinking in those terms but when you look at the studies they actually run,. It's mostly leveraging between subjects variability, right? There is now a stronger push for methods that use repeated assessments or you can look at variability within people but I think it's not yet the norm.