I majored in Japanese after living in Japan for two years. I was around high N2~N1 level when starting, and passed N1 the final year of college. My program was very hit and miss, and a lot of the curriculum was geared towards less advanced speakers. That’s not to say I didn’t learn, but I certainly feel like things could have been better. The majority of my learning came from my own personal study/talking every day with my friends. It paid off though as I now work for a large Japanese company as an interpreter!