That would be assuming the French labor market is efficient at selecting candidates for productivity, but given the general rigidity of labor laws in that count

That would be assuming the French labor market is efficient at selecting candidates for productivity, but given the general rigidity of labor laws in that country, the fact that productivity is pretty much a bad word culturally ("bad Americans capitalists greedy for more money at the expense of the average worker" kind of rhetoric) thus generally not trained (unions protest) let alone praised (most popular philosophers/influencers tend to be left-wing)... I think that's a pretty wild assumption to make. I don't know what supports it. Another angle: many studies tend to show that overworked people fall in productivity past some point, whereas generally "balanced" individuals in terms of workload and pressure and work/life balance etc. tend to perform great. It shows at the highest levels too — think athletes/sports with too-busy seasons, how we tone it down a notch to preserve performance, think how sleep deprivation is the worst you can do to productivity, etc.