Don't forget "subbotniks" ( https://en.wikipedia.org/wiki/Subbotnik https://en.wikipedia.org/wiki/Subbotnik ) - on weekends many workers would "voluntarily" do

Don't forget "subbotniks" ( https://en.wikipedia.org/wiki/Subbotnik https://en.wikipedia.org/wiki/Subbotnik ) - on weekends many workers would "voluntarily" do unpaid labor like cleaning city parks, etc.