This is so dependent on the kid and the school. My HS DS plays one sport and is involved in a few other things that don't take up much time. The biggest loss of time for us moving from MS to HS was that his sport starts a few weeks before school starts so we could no longer take a family vacation in August. Now a rising junior, DS has a summer job which limits our trips to see grandparents etc. even more.
During the school year, when his sport is over, he often comes home right after school. And while he takes really hard classes he is content to make mostly "B's" so homework hasn't been a huge issue either, although he probably works an hour or two a day outside of class.
My second kid hits high school next year and this DC plays 3 sports and has a very active social life. Still, winter/Christmas break, in particular, will continue to be free for us.