Depends on the speed limit you setup and how much Pokemons/Pokestops are near your location that you specify. Actually it acts as a human player. You could also setup car driving mode which is a lot of faster - but you should have in mind that this is not the very best option to act as a regular human player.
You can put it anywhere you want. Mine is in Santa Monica, CA. Its huge non stop area. Other large cities are good too.