The calendar is not a museum piece. It sets living religious practice today across the communities that use it, Zoroastrians in Iran and the Parsi communities of India and Pakistan chief among them, and the split between the Shahanshahi, Qadimi and Fasli tracks is a genuinely present disagreement rather than a settled historical footnote, since it means different Zoroastrian communities can keep Nowruz, the new year, and Mihragan on different Gregorian dates in the same year depending on which calendar their community follows.
Traditionalist Parsis in India have generally kept the Shahanshahi or Qadimi reckoning for religious observance even where Fasli has been adopted for civil convenience elsewhere, and reform movements that pushed for the Fasli calendar in the early twentieth century did so explicitly to restore the seasonal accuracy the older calendars had lost through centuries without a leap day.
The five Gatha days at the year's end are still kept as a period of reflection and charity before Nowruz, echoing the hinge role Ayyam-i-Ha plays in the unrelated Baha'i calendar, and Zoroastrian households still time major rites of passage, including initiation into the sacred cord and shirt, by the calendar's month and day names rather than by the civil date alone. Which version of the calendar a family or fire temple follows is, in practice, still a marker of communal identity and migration history among Zoroastrians today.