I personally avoid all such roads with 45+ mph limits, with so much traffic that people would have difficulty passing me. Those types of roads are abundant in my area, but thankfully my commute despite being mostly rural avoids all those roads. The route that I used to take when I first started commuting, aside from passing 3 school zones (really sucks during the school year), also has a large hill on a road that gets a LOT of traffic, especially semi trucks (on a 2-lane no shoulder road) that are barrelling along at 50+. That is NOT fun trying to huff and puff up that hill. So I take a different route now that's only 1 mile longer and less climbing. Sometimes I'll take the old route going home, which means I can fly down that big hill and then turn off soon after, but not in the mornings.

But even so, I've been commuting the same route for nearly 4 years now, and I haven't really felt like any such anger or aggression has been building up over time. Sometimes I see some of the same cars, sometimes not. Sometimes people have to slow down and wait for a few seconds, sometimes not. The wait is never more than a few seconds, and sometimes I'll pull off at a side street to help people pass so they don't have to wait for so long. I usually welcome a break anyway.

I know people don't like to slow down, myself included sometimes when driving my car. But people just have to get over it that there will always be various things on roads that require slowing down momentarily, even for just a few seconds. That's life.