Just last night I headed out planning to ride the local roads for an hour, but ended up exploring a long back road with no cell service… went about 95 miles over 2.5 hours.
The road ended up coming out exactly where I thought. But on 30 miles of back road there were maybe two dozen ranches, no cell service, and I only passed two cars the whole time. Would've felt a little better having the GPS with me. Plus it was approaching sunset and cooling off quickly. Sometimes you reach a point when exploring time is done and you're ready to get home NOW, though I'm glad that wasn't last night.
But the other thing I had forgotten about is on an unfamiliar curvy road with limited visibility around terrain, having the GPS running without a route and zoomed in fairly close can be a huge help in knowing what's coming ahead, which way the road curves and how sharply. Taken to the extreme it's a bad habit. You can end up riding the map instead of the road. But as a tool to help now and then, it's great.