We also worked to give them the basic tools they needed for independent studies and encouraged them from an early age to spend even five or ten minutes working on something with us nearby, but not watching over their shoulder. English which made it much easier. This method worked for three years. During this same period, my fourth child used a different BJU English textbook, but she participated in the older girls' history and science studies, while the my older son worked on a higher level independently. So, for some years, we were able to cover some of the same subjects with some of the children at the same time, but it was unrealistic to think we could do this all the time for every subject.
Some children prefer to work alone, rather than in groups, too.
For several years now, my older children have preferred to do mostly independent studies, with the exception of occasional unit studies. We no longer use as many textbooks, but have a traditional high school on CD-Rom program that the teens are continuing to use, along with reading a large variety of good books and writing. Some things go over my youngest child's head, that's fine. There is no pressure. Having a basic structure to our day, yet allowing room for flexibility.