Cannot agree any more; this is precisely the stance I took myself in 'high school' (dutch) with - thank god - support from my parents. (mental note: support my kids when they're doing this themselves)

IMO there's no point in forcing yourself into doing more work for subjects you really don't care about.

Luckily, here in Holland highschool grades don't really matter that much unless you're trying to get into med-school.