It depends on how easily and willin

It depends on how easily and willingly a person is influenced by the accent of the people around him.
When I first "went away to college" I encountered for the first time in my life many different people with regional accents. In some conversations it took less than 15 minutes before I would catch myself speaking somewhat more in their accent, completely "automatically". In other cases I sensed no such change. Maybe in the latter cases I did not admire them as much as interesting, intelligent people? I don't know.