I am sure there are a few drivers out there who are following to close. I can tell you that I would feel much safer in 65' of semi following at one truck length,than 15000'fiver with a 3500 in front of it,with one length.
The reason? Much stiffer and capable suspension and much better brakes.
However,in my days of driving there were always those who would get agreivated and go to riding someones bu!!. There was also some idiot cutting cars off and doing more than twice the speed limit to.
(This is one of the many reasons I quit driving truck,I didn't want to be associated with such idiots!)
I would always give one truck length and expand from there,bad weather,slick roads,visibility,ect. The thing is (as stated above)some idiot will always cut in front of you. All I can say is keep your cool and your distance.
------------------
95 Dodge 2500 Luverne grill guard,headache rack,running boards and Amzoiled. Soon to be mildly bombed. 84 Dodge d-150, 318 Hooker headers,Edelbrok intake,mallory ignition,Carter Afb,Accel coil,and Custom dual exhaust. Boat,fifthwheel,motorcycles,and shop. 72000 as of 3/1/01,not even broke in yet. Old Dodge 126000 miles and running better than new.