GPS units are completely unnecessary for riding. I track all of my rides in Starva, but navigate using PDF maps saved to my phone. I make the map using TOPO! software (since discontinued, but other topo map software is available), and add annotations on the PDFs to list either road names and mileages at towns. The maps show all roads and topography, so they are great for navigating. I then leave my phone on airplane mode and open up the PDF map in Acrobat whenever needed, while Strava tracks the ride in the background. I often ride in very remote areas on gravel roads, and have not had problems navigating this way. If I'm adding some singletrack in the ride, I'll also carry a compass to help with navigation.

Cue sheets are nice, but can lead you astray if your odometer is not calibrated well, of if the cue sheet itself has errors. This happened to me on a recent organized gravel ride - the cue sheet kept getting more and more off the longer I rode, and was about 2 miles off halfway through the course. I wish I would have made a map for that ride as it would have been much easier to navigate.