First of all, just to make sure there are no misconceptions here, as I discuss in much greater depth in this blog post I wrote earlier this month, contrary to popular belief, Ares was not the patron god of Sparta, nor was he one of the most important deities there. He was certainly worshipped in Sparta, but his cult there was relatively minor. The most important deities in Sparta were actually Zeus, Athena, Apollon, Artemis, and the Dioskouroi.
As I discuss in much greater depth in the blog post, Ares was never a very popular god among the ancient Greeks because they saw him as embodying raw, savage bloodlust, undisciplined slaughter, and violent devastation.
Ancient Greek religion revolved to a large extent around bargaining with the deities; someone would typically offer a deity prayers, sacrifices, and/or dedications in the hope that the deity would give them something that they wanted in return. Generally speaking, the Greeks worshipped Ares in order to keep him appeased so that he wouldn't unleash his wrath upon them, but they generally did not see him a god they could trust to bargain with or hold as their patron. As such, he was rarely invoked.
There is, as far as I am aware, only one ancient Greek city that seems to have worshipped Ares as its most important deity: the city of Metropolis in Ionia. As Christina Sponsel discusses in her 2017 master's thesis "Der Areskult in Metropolis (Ionia)" (which is available here for a PDF download), the cult of Ares in Metropolis is attested from the second century BCE until the third century CE, meaning it dates to the Hellenistic and Roman eras—not the Greek Archaic or Classical Periods.
Sponsel's study relies primarily on coins and inscriptions. She observes that there are apparently more surviving inscriptions pertaining to the cult of Ares from Metropolis alone than there are pertaining to the cult of Ares from all the rest of Asia Minor put together.
For further reading
On epichoric Greek religion in general: