I was trained in a bike shop around '81 or so and went on to work in several shops on the East and West Coast. The cool thing about working at a shop from a learning perspective, is that you're forced to work on things you probably never would on your own, plus you work on many different types bikes and gear teaching a lot of different ways of doing things.
That said though the internet and forums like this one can be a huge learning aid. When I got back into riding about 2 years ago I hadnt ridden or worked in a shop in 25+ years, and I was pretty rusty. I used this forum, Youtube, and online articles to help me get up to speed again on working on the bikes my wife and I ride. I still use those resources regularly in fact..