When roundabouts started appearing in central Ohio, how they were supposed to work wasn't entirely clear to me. Then I saw one up close, and it made sense. And the key is to see it not as a circular roadway with entrances and exits, but as a box formed by crossing one-way roads. With this insight, not only can I easily grasp how existing roundabouts are supposed to work, but designing them is much less mind-boggling. I think when a roundabout isn't marked correctly (such as at the end of FL 60 in Clearwater Beach) it's because the engineers don't understand this equivalence concept. The diagram below illustrates the concept. Each box highlights one intersection, with equivalent intersections in matching colors.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fvidthekid.info%2Fimghost%2Froundabout-equiva-prev.png8.png&hash=aa41d5a0f25cd4d33ffbae20eb5c835e8b1ca78a) (http://vidthekid.info/imghost/roundabout-equiva-full.png8.png)
Oops, I forgot to fade in one of the approaches...
I'm not sure this is helpful, as it doesn't help with the 'yield to circulating traffic' rule that governs roundabouts. Circular roadway with entrances and exits helps with that, though also isn't great unless dealing with large roundabouts.
That said the markings on the one-way streets diagram on the right makes that clearer than the roundabout diagram on the left.
That diagram reminds me of a Town Center Intersection:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRandom%2FTCIsandiego_zps47e6c027.jpg&hash=03de3b6911b0c914b0aced5981f5d6b06c3dbb9e)
https://www.youtube.com/watch?v=rCQn89wItTY