Instead of turning left at an intersection with a light and dedicated turn lane, I find it will often suggest I turn left then right then left to skip the intersection. It always turns out worse.
To reiterate, though: at least until a few years ago, according to PMs involved, Google Maps was tuned to keep directions shorter and simpler to read, describe (if you're a passenger) or even remember.
I find Google Maps _vastly_ underestimates how hard it is to turn onto a major artery without a light. It seems to think that turning left across three lanes of traffic without a light is "free". In practice, I have been stuck making these turns for 10+ minutes before. I've noticed it underestimates bridges as well.
> Sometimes it feels to me as if, over time, it learns from routes that it suggests and I repeatedly avoid, but that might have been just a coincidence and it might have learned that from aggregate data, not just mine.
That could be the case. Given my usage of Google Maps was less than once a month, it may not have had much to learn from me. I would also rate these poor experiences as bad.
Chicago
