It all depends on where you are. Just the other night our County Engineer explained (in an unrelated context) that all our county roads were originally wagon trails, and most of them have been improved very little since then. Some of them have not much more traffic than they did when they were wagon trails - or even less - and those are the ones that are great to ride on. They're just wide enough for two cars to pass, NOT wide enough for a car and a tractor, have very short sight lines (1/4 mile MAXIMUM) due to hills and curves, and if the speed limit has been reduced at all for residential development it's a minimum of 45.

But then there are county roads, not legally or physically distinct from the good riding roads, that are convenient for cars to get from point A to point B, and have a traffic load of 100+ cars per hour. Those are the ones I just don't ride on, no matter what. Either I add 5 miles to a ride to avoid them, or I drive.

Usually there's no place to pull off, since there's no shoulder, just a steep ditch at the immediate edge of the road surface. If there is someone's driveway to pull off into, it really wouldn't help, because you'd have to wait until 10 pm for traffic to clear enough to re-enter, and I don't ride ANY of the roads around here, busy or not, after dark.