> "Another important factor is the extent to which part-time work is widespread, […]"
I would argue being a "hard worker" means efficiency, not total amount. Sadly I don't have any data on that, or even any idea how to measure this.
GDP is a pretty rough metric for efficiency, but it's among the better ones that are collected somewhat uniformly.
"average hours worked * number of people working" is an approximation of total of person-hours worked (approx. because both numbers are probably cleaned up a bit in incompatible ways)
The result would be the value a person in the country contributes to the GDP every hour (on average), which should serve as a reasonably proxy for efficiency.
https://www.oecd-ilibrary.org/economics/gdp-per-hour-worked/...
Of course, efficiency can mean things beyond productivity.
Is there a "GDP of only the industrial sector"?