Here's how we manage DD9's homework approach:
- DD is ordered to "go play" immediately after school, unless there's some time crunch because of imminent scheduled activities.  She needs to detox.
- DD determines what homework to do and in what order.  We only prod her to make sure that all of it is done.
- DD is highly social, so isolation during homework is a terrible approach for her.  It would feel like punishment to her.  Even if she doesn't need any help, I end up sitting with her while she's working. 
- DD is highly motivated by extrinsic rewards, so we shamelessly pay her for grades.  To improve immediacy (because 9 weeks is A LONG TIME at that age), we give her small rewards each time she brings home a paper with a letter grade on it.  To short-circuit her own perfectionism, we have a reward for Bs as well as As.  Those grades are starting to become their own reward system.