I did this image up for curiosity's sake to see how the regions compared in this regard.

Now, this doesnt make mean too much without context, like, many of Sinnoh's Routes are long, while Unova and Kanto had a lot of short ones. But then, Unova also had a lot of Bridges.

Plus, towns can range from things like Tapu """"Village"""" to huge things like Lumiose. While places like the Pokemon Leagues outside Ever Grande, Royal Avenue, Village Bridge and Ruins of Alph are debatable. Though the games dont treat them that way, people certainly live or work there.

Anyways, what is the optimal distribution of Routes and Towns in your eyes?