In my work as a Faultsman, I used to be sent to the far-flung areas of our PoCo district.
After a while you would get used to the different areas road names and what have you.
Having said that, I had a lap-top with Line-CAD software on it, GPS built into a TUMONZ mapping system and a tracker installed in the Faults truck that told the Control room where I was at any given time.
Line-CAD used to instantly tell you where the fuses/transformer/pole was, as it had all been mapped out in 2001 and is updated every day as to changes in our Network.
As opposed to pure Navigation software, this used to tell you a route based on a straight line.
Never once did it send me on a wild goose chase.
Biggest problem here in New Zealand has been getting proper maps, TUMONZ solved all of that .
I also agree with Hal, nothing can substitute good map reading skills.
As a Rotary-Wing pilot, I'd sooner trust my own instincts, rather than anything Electronic, being up in the air.