This is effectively what cyberschooling allowed us to do with DD for 8yr (from 3rd through 12th grade).
I've detailed elsewhere what the problems were with that approach, but the bottom line is that it probably depends a lot on the student's personality. DD only really *needed* a few hours a week to complete "school" and then she was free to do other things that were more appropriate for her cognitive development.
This was our way to seeing to the credentialing side of things while balancing her need for more meaningful intellectual development-- it worked because her acceleration (3+y) meant that we needed the credentialing bit in order to unlock high school level opportunities like internships, summer programs, etc.
I'm not sure that I would do it again, honestly-- it was a lot of trouble, and aspects of the model were SO inappropriate-- and downright damaging, even, for a student with perfectionism issues. It also required a lot of parents (though to be fair, all of our options would have, since the only real alternative was full-time homeschooling).
HTH.
