As far as I can tell all those links you posted were case studies involving public administration jobs and bureaucracy. Parkinson's Law is explicitly about this.

It is not at all clear if (or how) productivity would go up in most other jobs, including construction, factory work, barbers, nurses, garbage men, chefs, etc. While technology may make it possible that people are productive per hour, there is no study or even pathway for how a chef (for instance) could produce more meals in 32 hours than 40.