A bit of celestial knowledge can be a god-send.
Yes indeed! In the case I mentioned, we had started before dawn on an ascent of Orizaba, the tallest of the Mexican volcanoes. My companion was navigating with his compass. It was a beautiful night and I had Polaris in sight,so we got straight quickly. The considerable variation was probbly due to iron in the surrounding lava flows.
Give me a starry night any day....