Good summary. A lot really has to do with both the AI's intentions with naval expansions - and the map makers understanding of how the AI interacts with the markers.
Each AI can, and often does, have different parameters for WHEN to expand, and how far to expand. As a result, the experience can vary rather wildly.
The AI developers have recently been talking about some logic to better understand what kind of naval investment is necessary, depending upon just how big a map is - and what % of the map is actually water. The idea being that the AI becomes aware that no matter what the markers may indicate - this map just isn't viable for naval work - or it's so significant that it should work much harder on naval.
