The trick with sensors range is that it should be dependant on the ship location itself when in fact it is tied up with Planets territorial extent... thus some of the confusion we all "think" happens when considering any sort of cap value (be it 15 maximum or whatever we could fit on bigger Hulls by adding numbers).
I first noticed this weird stuff on Immense maps by sending out a few X-Worlds' SpyShips in the open with their corresponding new Supporter component module (Which has range waaaayyyyy beyond defaults), i then realized that Support & Sensor are not that far off each other's 'gameplay principles" when you're trying to detect anything when these ships are far away from your own ZOC or influence range.
If that feature would be named 'Radar', then the illusion itself would vanish simply for the fact that we instinctively think of Sensors as being an ability to see within a radius rather than a sector based calculation variable to the exact location of the ships as it relates to planets' own sensory range.
Another way to detect this strange "incoherent" area of detection is to turn the mini-map feature on-off a few times while a ship travels outbound (faster moves per turn helps, but that again has to do with the XW engine speeds) and comparing what if anything showed up on the UI revealed by the range applicable at that particular moment.
Besides, EyesoftheUniverse omnipotent maximums bonus never made any sense, to me at all. Otherwise, all previously built ships with sensors WERE a waste and everything afterwards simply means we don't have to put sensors on ships anymore. Okay, the tactical gameplay balance has tilted - gotcha; but, then why have a Cap under these conditions?
Don't forget this IS a turn-based-situation - should it become RTS, then it would make a whole lotta rational difference to have such caps on sensors **and** on range that are also relative to map sizes.