On 2015-11-28, Don Y wrote:

People behind you tend to *stay* behind you. So, wherever
their headlights are (focused) now, they will remain there
for the foreseeable future.

....unless they are following you at half a car-length and/or driving
one of those 4WD "land yacht" trucks/suvs and their "illuminate
Cincinnati" headlights are "in yer face".

Sheesh! You relate all the proper technical answers, but seem to have
never done any real life commuting or even any real driving. I think
you need to get a "real life" clue.

nb