My own observations were that roundabouts tended to perform better than intersections with time division utilization and also didn't require any signaling infra

My own observations were that roundabouts tended to perform better than intersections with time division utilization and also didn't require any signaling infrastructure. Modifications to roundabouts that added dedicated bypass routes for higher traffic / shorter path (merge to closest output without being part of the main queue) were inexpensive upgrades. The same general observation also applied to higher scale variations where the core loop was either factored out entirely (every route has a dedicated path); applying more complexity (expensive) lead to better results. Of course the real world has different needs than this over-simplified simulation. Terrain and political situations impose limits on usable work area while use patterns can vary widely. Worse solutions that used to work in the past can be woefully incorrect as the world around them changes. The example that comes to my mind is the pattern in urban areas, especially like Seattle with heavy geographic constraints that make alternate routes untenable, where the old "most commuters go in to the city in the morning and leave in the evening" break entirely as jobs flee the expensive urban core and leave workers trying to traverse the choke points where cross traffic was never designed in.