That's an excellent and very practical question. As someone who's worked with city planning departments, I can tell you there's no single magic number. The recommended frequency depends heavily on a few key factors. Location is the biggest one. A trash can in a busy downtown square might need emptying 3-4 times a day, while one in a quiet residential neighborhood might only need service twice a week.
The type of area matters immensely. High-traffic zones like transit stations, tourist spots, and commercial districts demand daily, sometimes even multiple daily, pickups. Parks and residential areas can often operate on a set schedule, like Monday, Wednesday, and Friday. The volume and type of waste also play a role; bins near food vendors fill up faster with messier waste.
The best practice is implementing a dynamic schedule. Many modern cities are now using "smart" bins with sensors that alert sanitation crews when they reach 70-80% capacity. This data-driven approach prevents overflow and optimizes routes. The core principle is consistency and observation. A set schedule is a good start, but it must be adjusted based on real-world usage patterns, day of the week, and seasonal events. The ultimate goal is to empty the can *before* it overflows, maintaining cleanliness and public health.