Eh, I think every industrial society has independently arrived at something like 36-44 hours of factory time per week (plus overtime up to a max of something like 55 hours) , simply because that's the actual optimum[1]. While tariffs might work for other stuff [2], I think you're right that they can be a narrowly applicable scalpel, but plausibly you accidentally picked a bad example.

[1] Caveats apply. For example more advanced machinery with higher stress may necessitate shorter shifts; while highly motivated creative work might permit longer shifts at times.

[2] Adam Smith -for instance- was mostly against tariffs, though he identified certain exceptions such as national defense reasons.