Which do you think would be more important when going to a new place: being able to understand and speak the language like a native, knowing the customs and practices of the place, or understanding the streets like somebody who has lived there for decades?
edit: as somebody described it, it’s language vs customs vs lay of the land
Personally: etiquette.
Maps and dictionaries can mostly solve the other two problems, but if you come out as rude or do weird stuff, nobody is going to tell you and you could offend a bunch of people for nothing.