Calculating the Buddhist Lunisolar Calendar

Greetings in Dhamma,
I hope all is well with you. As the Buddha laid down a rule in the Vinaya that forest-dwelling monks (āraññikā) should learn the lunar mansions (nakkhattapadani), either in part or in detail, I would like to inquire about your take on to what extent learning should happen or perhaps has already happened. What is your knowledge, practice or general opinion on this point? Thank you!