Earlier quoted context omitted.
In Germany you used to start your apprenticeship at age 14.
Do the apprentices work 15 hour shifts 6-7 days a week? If so, I believe that is unhealthy, both mentally and physically, for anyone but especially a person whose body is growing and needs more rest than an older person.
For the post-WWII generations 12 hours 6 days a week should have been the absolute maximum. 8-10 hours 6 days a week (with the 6th day less hours) should have been more normal.