In fact, you will
rotate through the whole list INSTANTLY. As soon as they become the world's dullest person, the person who was next-dullest is now, instantaneously, the world's dullest
person.
This even accounts for the
birth of new, increasingly dull people. Whoever is the world's most dull person will constantly hold the title, except for an
instant during which someone else who had never held the
title holds it and then becomes less dull than
the world's dullest person.