I think in an ideal world, I’d set speed limits to be higher than they are now - say, (spitballing) 100mph for interstates.

I suspect many cars on the road can’t even be driven safely at that speed, and then you have to account for the driving ability of the average person.

You’d have more cases where there are high speed differentials too with some only going 60mph, and others going 100mph, increasing the amount of passing.