I don't think they do actually, of course a guide dog will learn a few common routes but the blind person will know the routes and call out left right straight on etc. The guide dog is there for pacing and stopping at the right points (crossings etc).
I did a few months voluntary work at their place in Woodford Green, fascinating time.
lol, I am loving the idea that a Guide dog is some sort of 4 legged sat nav.
The dog is there to stop the handler bumping into things or stepping off kerbs etc or finding a counter etc. OK with a regular route, the dog will get to know it, but it is the handler who knows the route. He doesn't just harness the dog up and "to the pub".
As I understand it, the owner walks where they want, the dog merely keeps them out of trouble by refusing to budge if it doesn't look safe. (Hopefully.)
I was speaking to woman who had a guide dog and she told me of another guide dog that was wandering around M&S with a Battenburg cake in its mouth. The owner was totally oblivious to this until an assistant went up and told her.
It seems that they can get quite good at stealing food without changing their gait, the blind person has no idea that a crime has been committed.
They do fantastic work and I admire people who put their safety in the hands/paws of a dog = but it gives them independence and the ability to go and earn a living.