I live in Southern New Hampshire burbs, where there are many trees and rolling hills.
I myself get less than 10 seconds in most of the areas I commute with my new 8500x50.
IO can effect this, but in several towns I drive thru they use K band CO.
Usually a single chirp then a short period of nothing followed by a quick ramp up.
What kind of warning times do you see with your RD?