If you look closely at the clip of the map earlier in the thread, you will see that the sectors on the edge of the map are not 25x25 sectors. The little bit of white "edge" encroaches into the sector, making it smaller. A full 25x25 goes into the white "edge" and ends at the tan part. Which possibly means that the white "edge" is still part of the terrain. Yes, I actually held a lined sheet of paper to my monitor. Yes, I could very well be wrong. Not saying anything about gaming the game or who is right or wrong, just pointing out that the fringe sectors are 25x25 if you go all the way thru the white to the tan.
Fury