That's an excellent question that cities worldwide grapple with. There isn't a single magic number, as the ideal frequency depends heavily on location, foot traffic, and season. However, a good baseline for a moderately used urban area is once per day. In very high-traffic zones like transit hubs or commercial districts, emptying might be needed 2-3 times daily. Conversely, quieter residential streets might manage with service every 2-3 days.
The key is preventing overflow, which creates litter, odors, and pest issues. Many forward-thinking cities are now adopting data-driven approaches. This includes using smart bin sensors that send real-time alerts when they near capacity, allowing for efficient, on-demand collection rather than a fixed rigid schedule. This not only keeps public spaces cleaner but also optimizes fuel and labor costs for municipal sanitation departments.
Factors like local events, weather (hot weather accelerates decay), and tourism spikes must also be considered. Ultimately, a combination of a reliable baseline schedule and flexible, technology-enhanced responses creates the most effective system for maintaining clean and pleasant urban environments for everyone.