When I had risers, I had a cheap convex bar-end mirror, and I used it all the time to "maintain situational awareness", though I still look over the shoulder before doing anything involving traffic. I like being able to see what's going on behind me, while still seeing what's going on in front of me!

Now that I have trekking bars, I bought one of these, and if I don't like the limited view angle, I'll stick one of those stick-on convex mirrors on it.