When my wife talked me into getting out of the marines so she could go to grad school, I somehow ended up in a A&P program. I finished the airframe and then she finished grad school and I never worked in the field. One thing I was amazed by was how little you actually have to learn to get licensed, and how much of your real training comes in the field after you get hired somewhere. We had to learn how to dope fabric on a Piper Cub and rivet patches into a Cessna Citation--the largest plane at the school. Doping fabric and gas welding steel tubing is archaic knowledge in the current fleet. My year at that school played a large part in my decision to avoid airplanes. You get licensed to work on 50 year old technology, and then sent out to apprentice on real planes. I'm guessing that Boeing and such offers lots of training schools for follow-up education for A&Ps. The school I went to would have in no way prepared me for duty on a modern airliner. I can form and rivet a beautiful patch on an aluminum wing, but a Beech Bonanza isn't a Boeing 777.
As my grandma (who would be 108 this year had she lived, bless her soul) used to say, "Lord bless us and spare us."