It's been my experience both as someone who has been through school and close observation of my own children as both students in schools and formerly home educated, that just our innate nature as human beings - we tend to retain long term, rather than just impress short-term, that which is relevant to our tangible needs and interests.
When I left school, I learned very *quickly*, all kinds of things not taught in school, not because school "taught me how to learn" but because I was passionate about the subject.
I've retained very little of the material that actually had nothing to do with my long-term life. Sure I could get the grade on a test paper, but would I be able to manage it today? No.