Take my personal experience as an example. My class teacher (Chinese teacher) in Grade Two is very annoying. Almost everyone in her two classes hates her, so I got the lowest grade in Chinese in Grade Two. Then she left in the third grade, and we changed the head teacher. My Chinese grades have changed directly from the countdown to the average or even the average.
Then talk about the teaching level. Our high school physics teacher is a young man who just graduated and has been a teacher in the class next door for more than ten years. Even if we like our physics teacher again, our average score is always much lower than that of the class next door. Then the third year of high school was divided into classes and changed teachers (the original one taught the second year of high school), and the results of choosing physics went up at once.
Of course, more depends on the individual. Graduates from key schools are definitely better than those from ordinary schools, because the foundation is different.