Leftist revolutionaries have long been in the habit of reworking the calendar so as it make it easier to force the population into new habits and new ways of life better suited to the revolutionaries themselves.
The French revolutionaries famously abolished the usual calendar, replacing it with a ten-day week system with three weeks in each month. The months were all renamed. Christian feast days and holidays were replaced with commemorations of plants like turnips and cauliflower.
The Soviet communists attempted major reforms to the calendar themselves. Among these was the abolition of the traditional week with its Sundays off and predictable seven-day cycles.