Depending on locality. A “Normal” apprenticeship used to be 5 years (10,000 hours) Plus 720 class room studies. Today in America some folks consider 12 weeks enough training to learn the basics then learn OJT.
Seeing the caliper of the new home construction and the use of fast cheap materials 4 years apprenticeship is more then enough.
We have “plumbers” upstate New Yawk that are lucky to be able to read 4th grade level.
Canada has a fantastic training program going on .