> Thinking forward, how would this part of the code cope if jPointsAreConsecutive=...

That's not being addressed at all. I don't have any business drivers or user stories to justify spending any time on it. I'm happy to be blissfully ignorant of the implications!

You could rightly push this from a robustness point of view but I suggest it's not something we need to consider now, if ever.

I think this situation would mean it's the columns that have a varying number of points. That's not useful, even though it's technically possible. I think varying the number of points is only useful for giving rows a geographically similar distance between points.