This is based on my experience with driving. I used to drive car every other week from the city where I live to my hometown (230km give or take). I did the route several times for few years - and still I never could remember which exit to take on specific places. Then I decided to drive without navigation. It took few wrong turns and one try and now I remember my route without any problems.
~20 years ago I knew most PHP function by heart. Today I need to keep the rust documentation open.
I had roughly the same internet access I have now.
What you point out with the GPS likely happened because the negative emotion of taking the wrong turn built a memory for you.
I don’t mean for this to sound snarky, it’s an honest question: are there no signs? Having to “remember” which exit to take seems to indicate to me that the route isn’t drivable in any intuitive way (ie follow the signage to your city/block)
Because if there are signs, I just think this depends on how we individually use GPS assistance.
Signs take attention looking at. They often don’t point to where you want to go, but some other major destination along the way, or road names. Junctions can be confusing.
When I can, I like to drive without satnav, it makes me appreciate the geography more.
Maybe important to note, this is Europe. Going from one's country big city to other's country small city. It's not just straight single highway.
So I may be going to 123 Brown street of Pleasantville, and to get there I need to take number of random roads in my town, get to highway 10, then take ramp to Highway 20 West (which at this point is actually going South, because highways are wiggly but need consistent naming), then take exit 303 "Alabama Street" to go to Atom road to drive 20km to take right on Williams Boulevard to get to town of Pleasantville and take 3 more streets to go to Brown Street.
(also, note that I've found signs in different places be oriented very differently; in parts of Europe, you'll frequently have sings that indicate which way to a selection of big neighbouring cities; I don't really see that in North America)
And I’m someone that can walk around randomly and perfectly keep a mental map of the whole area.
To be more precise: studies have shown that passive learning is significantly less effective than active learning[1]. "Active" learning involves intentional recall, as opposed to passive review. Searching things is passive review. Racking your brain to try to remember the prototype of a function is active recall, which significantly strengthens the memory in your brain.
So, yes, this is the reason, and there's scientific evidence to back it up.