Siesta is depends of the country you go, probably most of latin American have siesta butt its depends on the city you'll go to if it's a big city not all people gonna sleep for siesta. If it's a big city most of the shop and etc will open for all days but if's not it'll close in siesta times and open again in the evening till night probably very late.
ARG has siesta for sure, I really love siesta not much study lots of party chilllllllll jajajja