I had math in school in a variety of different states in the USA and also in Cartegena Colombia. Schools varied from Montessori at the high end to piss-poor public schools at the low end. Despite the best efforts of teachers using a variety of styles and languages, I had no clue what mathematics was about until university.

Suddenly it clicked in physics class. I had a natural epiphany and I could finally solve complex problems. Damned if I can explain it. After physics I took linear algebra and DE. Difficult courses, but I UNDERSTOOD. Amazing difference. Inexplicable to this day.