Mine required about 8000 hours. A phd requires about 4000 (based on the theory of 2 hours outside the classroom for every hour in it). I had to learn metallurgy, electrical theory, trig, algebra, and physics. And that's BEFORE I picked up a torch. Every week I have my work examined by a fucking X-ray because lives and literal millions of dollars of ocean going freight depend on me being fucking awesome at my job.
To be technical though, most of that 8000 for my journeymans card was time on the torch. Only 700 hours was class room time. Roughly around what's required for a 4 year degree. The point I want to illustrate to you Top, is that it's a pretty intellectually demanding job at my level.