My high school maths was a waste of time basically, as I don't have use for it now, and didn't use it through uni either.....
Life experience teaches me more than school too, I would say that school has inspired me to learn more though, e.g. I studied history for 6 years at two different universities in order to get a research degree, however, at first I only chose the subject because our history teacher at high school inspired me to study this subject....
For me, history should be a compulsory subject always, as history is an interdisciplinary subject mixing many academic subjects: political science, economics, linguistics, anthropology, geography..and many more depending on case.
Funny enough, I don't work with history today, having done the history teaching and working at arsenal museum, PR for defence commando - I chose a different field: communications consulting in an international company!!!
Now I keep contact with "my subject" a few times a year by being an external advisor for undergraduate students at University.....so, I still keep "up-to-date" with history...