Depends on level of orthodoxy and time of year, I believe. I have seen some that are worn year round, and some that only go on for specific religious times, or when actually in Temple.
The question becomes one less of religious exemption, and more of cultural. If I wear an outward symbol of my faith, then I am at least passively proselytizing, and I think that that is what many actually take offense to. A Hijab isn’t just saying “I’m not as good as a man.”, but it also implies “I am still better than you.” Not saying that that is what the intent is, but that is the perception that causes the visceral reaction to such outward signs of religious affiliation.
Maybe instead of basing exemptions on religious beliefs, and more on actual cultures, we would be able to more objectively evaluate the value of allowing one to keep to ones traditions that have kept the culture together and viable for generations, while not allowing real public safety concerns to be trumped by arbitrarily derived rules from the man in the sky.
Cultures are meant to adapt to changing times, religions are not. Traditions can change to accommodate new ideas and different views, while still retaining their roots, sacred scripture and religious belief cannot.
Allowing someone of Jewish descent and culture, or even someone who appreciates their culture, to wear reasonable symbols to represent his ancestors struggles during special times is no different really than school kids in the US dressing up as pilgrims for thanksgiving. As long as it is realized that neither is more sacred or objectively useful (or even representative of actual history), I see no problem with it. I look forward to the day when Muslim women would wear the Hijab on special occasions to represent the struggles and oppression they overcame. The Christian cross could be worn at Easter times to represent bunnies and eggs (that one has always puzzled me, though, had Jesus been executed by beheading, would they worship an axe? Hanging, a noose? ). If policies that do not impact public safety are exempted to help a culture maintain it’s stability, then that can be considered a public good and it makes sense to make the accommodations.
As long as we give credit to the people who claim to be speaking for the supreme ruler of the universe, we cannot have any sort of secular law. If any law can be exempted “because GOD says so”, then every law can be, and the secular legal system falls apart.