Yeah, there is no need to put many nodes. I mean, I usually place a lot of them, because I tend to direct the AI to perform in specific ways (peeking from the windows, patrolling around important spots like stairs, etc.), but it's not exactly required.
The case I mentioned before happened when I was making routes for the TFTD luxury liner, the version which has both top and bottom parts as one map. So, pretty extreme, especially with all those countless little rooms.