I suppose it comes down to how you use the sat-nav, and what you expect it to do.
Hollibobs is one of the times my car Garmin gets the most use.
Amusingly, I tried to decline the Sat-Nav option at Denver last year, on account of having my own, pre-programmed with all my stuff.
But it was a 'free' option on my hire so I 'Had to take it, or I'd be charged for it when I returned the vehicle without it.'
It remained in the glove compartment for the duration.
I will have installed current maps for my destination, set up waypoints for my destinations, and checked the routes it will use.
I try to keep current with CN Europe and CN N.America.
I sometimes need to pick up some mapping for SE Asia.
And in Africa, I use ( and contribute to ) Tracks4Africa crowd-sourced maps, which contain the 'usual' routes and off-road tracks and sand-roads, as well as the Garmin mapping.