hi! this collection of posts on German stereotypes aren't strictly on the subject of "work ethic", but may be relevant and of interest
Discipline & military tradition
"German engineering"
What made the Germanic region such a powerhouse in mathematics in the 18th-20th centuries?
Is there a reason for why so many renowned scientists/inventors were German, historically?
I believe all of these posts have been archived by now, so if you have follow-up questions for any of the users, ask them here & mention the username to notify them