Trash piled up around a trash/waste can/container at London Fields Park, on a nice weather weekend, London

 

Reddit photo.

Many parks and business improvement districts provide more limited services on weekends, when these districts may have more patronage not less, but it doesn't comport with "business hours."

They need to have more frequent pick up on weekends.  

This has to do with planning for seasonality and 12 month parks.

Note that the park users are to be lauded for putting the trash at the waste can.  There are photos of Dolores Park on a weekend that are super trashy ("Enough litter to fill 460 bags of trash left behind by Dolores Park revelers over weekend," San Francisco Chronicle).

That's the point made in the entry, "Gaps in Parks Master Planning: Part One | Levels of Service" wrt parks that need more service than what is typical.  That goes for parks in temperate areas too.  In winter, parks tend to be used less.  But not in temperate areas.