Some of the most binding rules you will meet as a traveler are not laws at all. Quiet hours are the classic example: in parts of Europe, especially German-speaking countries, evening and Sunday quiet is a near-sacred norm, and noise that would be unremarkable elsewhere brings neighbor complaints quickly. Prayer times shape rhythm across the Muslim world, with shops in some countries pausing during prayers, and Ramadan reshaping the whole day, when eating and drinking publicly during fasting hours ranges from frowned upon to actually penalized depending on the country. Sabbath observance similarly transforms parts of some cities from Friday evening, with transit stopping and businesses closing.
Add siesta cultures where afternoons genuinely shut down, temple and shrine etiquette that restricts entry times or dress, red-letter days when noise and celebration are expected to pause, and neighborhood norms about late-night behavior that police by disapproval rather than fines.
None of this appears on a legal list, which is why the best sources are your hosts, hotel staff, and simply watching what locals do. The travel skill that ages best is calibrating to local rhythm rather than asserting your own; communities notice and reciprocate the effort, and the unofficial rules relax fastest for visitors who visibly respect them.