They absolutely suck when a train of cars forms and you can't enter the loop. Those are the dumbest roundabouts in the country. They don't adequately force cars to slow down enough to let gaps develop in the flow.

I'm not sure that slowing the cars down would help more. Its much easier to drive literally right behind a car at a slower speed than a higher speed.

Afaik, the general trend is to put a stoplight going into the roundabout for the few directions that cause a problem so that the "side streets" get a chance to go.

The other stupid thing about Carmel roundabouts is where they put them at every 3rd road crossing when it would have worked absolutely fine just to have the traffic going one way stop, because it's a neighborhood with thoroughfares and cross streets, and there is NEVER traffic on the cross streets.

It just makes the thoroughfares slower for no clear reason.