When I was in my training two of the three Fi's seemed to always want to use the GPS first, the maps as a back up, the reason being given was that it was easier when flying a heli to refer to the GPS , but even around the north of England the GPS was never as good as a old fashioned map with Hi Viz ink lines drawn showing headings and wind direction. Now that was 12 years ago and I would suspect GPS units are better now than then, but I would only really use the GPS as a cross ref for the maps on any long flight into unfamiliar territory.
How many people even today using Sat Nav in car's finish up taking longer or being presented with roads not suitable for HGVs and cars,
..No GPS is merely an aid to Flyers rely on it soley and you may not get to your required destination !
Peter R-B
Lancashire