Just out of curiosity, do all the Orthodox churches observe the same calendar of Saints?
The major feast days are the same, though there are differences on account of the Old Calendar / New Calendar practice. I think that most Patriarchates and autocephallous churches otherwise have their own calendars which tend to celebrate saints with more local connections (again, the major saints’ feasts are the same). For example, in Greece, especially my family’s part, September 16th is the feast of St. Gerasimos of Leontarion. It is a major big deal but you won’t find him listed on, for example, any American Orthodox jurisdiction’s website or on the Slavic ones or the Arab or Ethiopian or the Alexandrian calendars.