RV has each box interaction value equal to 400, exactly the same as SFB.coloin wrote:The SFB also had consistently low box interaction values - [eg filling of B4 for a given B1/B5]. see Presumablly RV has this property.

I don't think box interaction values are important, though: if you calculate the grid statistic BoxInt = sum of all 18 box interaction values, then you find 17-capable grids generally have slightly higher BoxInt stats than random grids, but only with an unimpressive good-ranking score of c. 56%. But maybe I'm just looking at it the wrong way.

Update: overnight, I found all 127 essentially-different ways of building a fully-entwined grid; the whole snake pit, you might say. I will report results from these soon but first I want to do a (completely pointless, I know) 16-clue search on one of the MCN 7 grids the popped out ...