When I started in the business, the apprenticeship was a 5 year progeam, BECAUSE the apprentice worked 4 day OTJ and one day in school. It was not a "five day classroom" which would have taken less time for the "book learning" but lost the REAL experience of putting it into practice on a daily basis. I addition, I got paid my regular pay for going to school, I did not have to pay tuition to do it. There are a lot of plumbers who learned on the job and are worthless for anything other than "bull work" working on new jobs, and others who know what's "in the book" but are completely useless when it comes to applying it themselves. Both of these types need a foreman to guide and direct them.