It is not clear why these seven were chosen to represent the whole church, though they are connected by being located on the main Roman road at intervals of about thirty or forty miles. ---(M. Eugene Boring, Revelation, p. 87)
The arrangement of the cities is geographically significant: the seven all lay on a main Roman road and formed a circuit, starting from Ephesus, the nearest to Patmos. (John Sweet, Revelation, John Sweet, p. 78)
That all seven cities chosen by Jesus to prophetically model the Church, were connected by a main Roman road is of great significance. This signifies that the whole Church on Earth, passing from generation to generation is unified, connected, and continued without fail by the Bishop of Rome, the Successor of Saint Peter, also called the Pope. The Angel of each Church serves as a moniker, a collective noun, for every single Pope who led for the duration of each respective Church.
The geographical circuit, starting with Ephesus and ending in Laodicea, prophetically mimics the full circle the Church will voyage from the First Coming of Jesus culminating in his Ascension to his Return, as well as conclusion in which God will wrap up world, even this Earth as we know it so to create a New Earth.