It is extremely helpful! I find a magnetic compass to be useless when compared to my good friend Sol. He always tells me what time it is exactly down to the minute of the day when he's up, and all his buddies do the rest at night.
Its a great tool to learn to tell time and direction using the sun and stars. Cloudyness can make things tough (only at night time of course), but there are alternate ways to gauge time with temperature at night.
I think someday soon ill post a defined way to help people find their time and direction at any time in the day with detail, but I just wanted to make that suggestion to folks. If you learn to find Polaris, and how the stars rotate around it, and can feel and understand the ascention of the sun, things get really easy quick, and you don't need those compass's anymore (still need the GPS for them caches though!)