seems that the reduction in time forced to cut down on crap - starving the beast so to say - and that would be the major reason for the productivity increase:

seems that the reduction in time forced to cut down on crap - starving the beast so to say - and that would be the major reason for the productivity increase: " In their research into working time reduction in the last few decades of the 20th century, for instance, Bosch and Lehndorff (2001) note how a number of workplaces have indicated that successful reductions in working hours have been closely tied to changes in the organisation of work — whether through workers gaining greater autonomy over work processes, or changes in operating times and shift patterns. Such reorganisations have clearly had a positive impact on productivity. ... The stated reduction in working hours did lead to staff actually working less as a direct result of workplaces implementing new work strategies, and through organising tasks via cooperation between workers and managers. As mentioned earlier, a central aim of both trials was to ensure service provision remained the same following reductions in working time. To be able to work less while providing the same level of service, changes in the organisation of work therefore had to be implemented. Most commonly, this was done by rethinking how tasks were completed: shortening meetings, cutting out unnecessary tasks, and shifts arrangements"