If we were considering a model where machinery was doing most of the work (between 70%-97% with current technologies, with no fear of technological unemployment), there'd be few working hours, but a problem shall always still surge from the lack of a material incentive: Why work when no one trumps no one?
Even if the work hours could be as low as one hour per day, we could assume a system of trust where a certain task is not given to one sole member of the group, but a group of them.
Tasks would not be equally distributed. The tasks would fit the vocation of the one doing them. And even so, not only that one person, but a group of people who would take accountability for the action itself.
The workflow distribution can be announced on a unified platform. Consider it a "facebook for the work tasks and projects".
Some technological solution which would put the tasks up for anyone to fulfill them, then distribute them between the people who would not mind to take accountability for them.
This all seems utopian in a sense, but we're talking about low necessity workflows. Most work done would be vocational-based and not necessity-based.
Psycologically, there are studies to be made in this area, technologically, we have the means:
http://www.joomla.org/
