Here are some observations by an American math teacher who spent a research assignment in Finnish schools. His main observation is: ‘Less is more’.
That means fewer years at school for the children and more time to play, fewer hours in a school day, giving adolescents a later start and more sleep, fewer teaching hours for the teachers, allowing them more time to prepare interesting lessons, less testing and therefore more time for teaching and finally: fewer topics in the curriculum, allowing teachers to go deeper into the subjects.
I see no reason why we could not apply these principles to education outside Finland.