Agreed, as far as smaller cities with a single family. In NYC, however, territory has never been geographically defined. Bensonhurst, Howard Beach and the former Little Italy are representative of this. All five families had crews in these areas. East harlem had members from 4 families.

Interestingly, there were still sub-territories dominated by specific NY families. Canarsie was exclusively Luchesse and Gambino, with relatively no members from Genovese, Colombo and Bonanno. Bushwick was exclusively Bonanno.

Mob presence in 1983, by neighborhood: https://www.google.com/maps/@40.6870867,-73.9538835,13z/data=!4m2!6m1!1s1mxiiJTnHpvUuwhc3HqNLejhF2UE498gm?hl=en