i think knowing a system by playing with it gives a much better perspective than simply theorizing about it. generally, if you "know" the system, you don't have to do much theorization -- the solutions are obvious

unfortunately, not everyone is suited for that sort of learning. and in fact i would say most people aren't able to "know" using any method. for these people a decent plan can be beneficial, but technical subjects require a minimal degree of playfulness. their capricious details aren't very forgiving to fine plans, and you'll probably find most of these people don't become programmers :)

... or they become java programmers?