It’s the little things that often take the longest to program, or at least make developing a feature take longer than expected. But I think flight simulation has reached the point where the details are what matters.
Trivial example: if we have a runway that’s shorter than 9000 feet and about an even multiple of 1000 feet then the distance-remaining signs (every 1000 feet) from the two directions may be too close to each other or even overlap. X-Plane 850 will detect this case and generate a single two-sided distance-remaining sign (like real life), so that the signs don’t obscure each other.
If the runway length is such that merging the signs would create too much error in their measurement, or we only have a sign in one direction, there is no merge.
The 850 airport code is full of tiny details like this.