Why you need to understand heterogeneity

Your average client is
A certain age
A certain education level
A certain income level
A certain marital status

So is that sufficient information to really know your optimal audience?

No, it is not.

There is still the matter of heterogeneity.

Wendy MacQueen wrote "Know Your Customer - It’s Not Just About Demographics Anymore"

By The Way - she does not use the word "heterogeneity" but she does discuss it.