I live in a smallish town (~14k in the limits). For the most part, cycling on major highways is merely unpleasant, there's a nice wide shoulder. Less important highways have less shoulder and less traffic. There's parts of the highway that I avoid, and parts where I won't go, but those are the parts with parallel streets in town, not the parts between towns.

It's also not so uncommon for their to be a trail with similar connectivity to the highway (lots of rail trails do this). I can ride to the next town/village over with about ¼ mile of actual highway riding. That's pretty recent, what with a casino paying for lots of trail and a new bridge being built on the US route, but there you go.