/Threadjack
Funny you mention that... my buddy used to live in FL. I went to visit one time and we were out driving around (maybe it was the night we went shooting) and I asked him about the reflectors in the street. There were random blue reflectors in the street (like the centerline reflectors). He had no idea what they were... I studied them for a bit, and then it hit me. Every place there was a blue reflector there was also a fire-hydrant... Growing up in small-town america it was a totally foreign concept to me; everybody knew where every fire-hydrant in my home town was...
...I noticed these blue slats woven into the State's right away fence....
There was only one...Wow!
Both of them?
Col. Mustard in the kitchen with the candelabra!
Oh, not that kind of mystery.
If you're talking about the fence between the highway right of way and abutting private lands, I thought they were put there by the farmers whose fields were right there to aim for when running their machinery long distances with no other distant landmarks to aim for, and to delineate one type of crop from another, even when the field is a single major type, such as one hybrid of corn from another.
Since they're placed by individual farmers for their particular needs, their patterns and spacings/placements would seem random unless you're that particular farmer.