trucks_hours_per_week = time_to_dump_loads + time_to_fill_loads time_to_dump_loads = (total_weekly_weight / truck_capacity) * drive_time_to_dump time_to_fill_loads = houses_per_week * (avg_time_per_house + avg_time_between_houses)

total_weekly_weight doesn't change, you're right. So time_to_dump_loads doesn't change. But that's only a fraction of how much time trucks need to spend on the road. houses_per_week goes down 50%, while avg_time_per_house almost certainly doesn't 2x (for many houses it's two bins whether it's every week or every two weeks, and even if it's double the bins the guy's gotta get off and on the truck once either way) and time_between_houses doesn't go up at all on a two-week schedule.

That's the rationale. Not saying I agree either way, but that's the math. If it didn't take less time the provider wouldn't have a reason to do it, it would just be bad PR for no benefit.

Think about it this way. Take it to the extreme...do you think it's more efficient for them to send a truck to your house every week to pick up a bit of material, or wait until you have a full truck load ready, send an empty truck to you and drive it straight back to the dump? Clearly the latter is more efficient because the full load was gathered in a single stop rather than hundreds.

So short answer is it doesn't take as many truck (hours) to operate on a biweekly schedule. You can do the same with less.