It's definitely a perishable skill, but as long as the basic principles don't change (math & celestial geometry), it's always a good fall-back. In this day of possible EMP events, the US Naval Academy reintroduced celestial navigation after having eliminated it from the curriculum in the 90's iirc.

I use a (plastic) Davis Instruments Mark 3 Sextant in the backyard to shoot sun and moon using a small dish of water to function as an artificial horizon. It's good practice.