I can not speak to the building trades. I can however speak to the skilled trades program in the auto industry. I am a diemaker by trade. The Ford program was 2000 hours of classroom instruction and 6000 hours of on the job, hands on training.

I completed my apprenticeship in 3 1/2 years and I enjoyed a nice 11+ years working in the trade before taking a salaried position with Ford for my final 13 years there.

I would think that most skilled trade positions are structured because they have to be. To call someone a slow learner because it might take 3 to 4 years to complete the program is an insult to tradesmen(women) in general.