Have you actually looked at a curricula? A lot of it is repetition from school stuff. Sure the Electricians in my example learned in 7th class how to transform Volt to mV or kV. But they often can't reproduce this when they start their apprenticeship (imo the schools are to blame here).
If apprentices don't have problems with that Kind of Math, can write readable reports they generally get a Lehrzeitverkürzung up to 1.5 Years.
Source: I actually read curricula of Apprenticeships, talk with colleagues who work in the Berufsschule if my pupils might have a shot at a apprenticeship (they never do)
Besides that we have longer apprenticeships 1) so that the "german workforce" is more skilled in general. 2) so that if they choose to become Meister to be their own boss they don't need to learn all the extra stuff.
> If you already knew the one thing, chances are you could've quickly learned the other thing as well.
That does certainly apply to abstract things but it doesn't apply well to craftsmanship. To quote RMS: A if-construct does not generate friction against the for loop. But if you bend the cables in the wrong radius, 20 years later when the plastic of the wire-insulation starts degenerating, you might run into problems.
> YAGNI comparing humans to programs? i like to live in a world with skilled human beings that can realize at least some of their potential. an extended apprenticeship might help some to do that.