Jewish holidays and work

Hi! I’m not Jewish, but I have employees who are. Is it safe/respectful to assume that they won’t be available for work on holidays, or should I wait for them to ask me for the days off? Right now I have them automatically scheduled off for Rosh Hashanah, Yom Kippur, Sukkot, and Shemini Atzeret / Simchat Torah.

Is that okay, or is it presumptuous or something? Should I wait for them to ask for it off?

Edit: I’ve followed the advice in the comments and sent an email to everyone asking for time off requests for the rest of the year. Thank you so much for all the help and advice!