"But I don't think I've ever spent time to learn a particular word - it's almost always enough to hear it in context once, and maybe get a chance to actually use it yourself once or twice, and you'll probably remember it for life."

I'd strongly bet against this. If it were true, SAT and similar vocabulary tests would be trivial to anybody who has taken high school English, and I think it is not the case that most people perceive the SAT to be trivial.