Bingo. This was mostly how we did our kids’ ECs; by the time that the oldest had a driver’s license, they could do more (and off-campus) activities such as swim practice and meets, since there was an extra driver in the family.
@thumper1 got it right: your kids don’t need lots of ECs, just ones that they are committed to and show passion about. For all those kids who have a hundred ECs on their resumes (or so it seems), I suspect that college admissions officers are not that impressed by the “mile wide and an inch deep” EC philosophy.
You’re doing fine, and your kids are doing fine.