According to my experience, it is totally depends on whether the school will spend effort in Music training. Like my friend's school, 一線學校 , they have wind band, but the school treat it as one of the extra curricular activities only.
Like LS, APS, DBS, YW and etc., the orchestra practice is not treat as extra curricular activities , they have practice through out the years, even in Christmas , new year and summer holidays.