Range generation trimming does unexpected things.
If you have a narrow 1 space wide passageway and you build a fire pit in the middle of it to extend the range generation down the passageway it instead cuts off the range. This is because fire pits aren't walkable/buildable area and so it sees the range beyond the just built fire pit as now no longer accessible. You have to carve space around the fire pit for the range to expand beyond.
The above causes other issues. For example if you build a firepit in a wall to extend the range beyond the wall, it doesn't do anything unless you have something to extend the range "around" the wall to the other side to reach the fire pit, then the fire pit "activates" and further extends the range beyond the wall.
This was incredibly confusing as I was trying to work with building walls as a new player and it took me a while to understand the mechanism on how range trimming works to avoid just completely breaking the building of walls
If the above doesn't make sense I can provide some screen shots.
I suggest changing how range trimming works and make it so that any building that is reached by existing range automatically extends its range, regardless if there's a valid consecutive connected segment of buildable area.