My first experience at "opportunistic learning" was when I was in technical school after basic training in the US Air Force. I was standing in a L O N G line waiting for lunch and the guy behind me had a few books from the base library. One was on digital computing theory (this was back in the 1960s) and I started browsing through it. I borrowed his copy and read it while standing ion the chow like three times a day for weeks, renewed it in my name, and went through the book twice instead of just standing there with my brain in neutral. That led to taking college classes at night and all sorts of trickle-down changes for the rest of my working career.
The little things can make a big change and I fully agree with your "snippets of learning"!
Will