At freeway speeds you should scan at least ahead to compensate for how much faster youll have to absorb visual information

There are two ways to look at this. Either 10 to 15 seconds down the road, which means looking where your car will be in 10-15 seconds. Or and this is the equivalent idea (normally), look to the edge of your vision on the road. Both of these practices are to ensure you are prepared for deviations (unexpected differences). While following another vehicle at highway speeds, it is good to give a minimum of 2-3 seconds between cars, this means that your car would pass an object that the care in front of you pass with at least two or three seconds.