EU-LFS, which I referenced, is published by Eurostat, is a core part of the official Eurostat data, and is survey-based, not derived from estimates of contracts.
Here is Eurostat's EU-LFS data browser for "hours worked per week of full time employment":
You'll note they include asking for the same information (estimates of hours worked) several different ways (with and without overtime, and asking separately for the overtime) and that they include instructions to the interviewer for confirming that the result is internally consistent.
EU-LFS is the main source of data on those aspects for the EU. Measuring overall productivity then comes from matching economic indicators up against hours worked.
Here is Eurostat's EU-LFS data browser for "hours worked per week of full time employment":
https://ec.europa.eu/eurostat/databrowser/view/tps00071/defa...
You can find the actual questionnaires used for carrying out these surveys here:
https://ec.europa.eu/eurostat/statistics-explained/index.php...
You'll note they include asking for the same information (estimates of hours worked) several different ways (with and without overtime, and asking separately for the overtime) and that they include instructions to the interviewer for confirming that the result is internally consistent.
EU-LFS is the main source of data on those aspects for the EU. Measuring overall productivity then comes from matching economic indicators up against hours worked.