Fairly sure at least one of the tunnels under the Mersey has a junction midway, no idea where it takes you as I always go strait on, but it does mean taking the wrong turn in the tunnel means that you would exit the wrong tunnel  Tangiers Orange - gone, missing her
Replaced by Ewok what a mistake - now a happy Disco Sport owner

Under Monaco we went through a bit of a maze but it was well sign posted. Sydney has some branching tunnels but the exits have good signage well ahead of the turnoffs. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Outback Australia the GPS wants to send you on hundreds of kms of detours when it is plainly clear there is a direct route. Often I found the road is not even there, not even a goat track.

The risk out here is that you will run out of fuel & then water!
 Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

My understanding is that tags and aerials should be fitted to the black dotted/hatched areas of the windscreen the largest of which is around rain sensor and rear view mirror fixing. Both of the dash cams I’ve used and fitted in this area have had gps and always pickup the signals from the satellites quickly after startup depending on the surroundings.
On the various route finders, I use Apple maps on an iPad (built in GPS) mounted to the left of the console and it is accurate enough to place me in the correct lane on a 6 lane motorway. As for routing, it is as random as the others mentioned here but that’s not surprising when you consider all the constantly changing variables.
If I really want to know where I am I switch to a digital version of the Ordinance Survey.