What particularly struck me about your plan is that you have not allowed for 'an accident up ahead'. At least on a handful of occasions has a hold up like that delayed me for hours. When you are stuck on an interstate without another exit ahead, all you can do is cool off and wait.

I'd agree with Michael that 600 miles on consecutive days leads to fatigue, of which you may not be aware until you are already an unsafe drive. It is the silent killer on the road, takes days to recover and stops you from enjoying anything at your destination.

Lifey.