You can actually screw them up: by our house (in California) they replaced a 4-way stop with a roundabout with no signaling on 2 of the ways, and a stop on the other 2. An absolute disaster, as the 2 ways without the stop assumed they had the right of way over people already in the roundabout.
After the neighbourhood complained, it's now a roundabout with 4 stops (not ideal, but not dangerous either).
After the neighbourhood complained, it's now a roundabout with 4 stops (not ideal, but not dangerous either).