I’m having a problem understanding thread counts across the sett. I cant get the numbers to add up. For instance:

A simple sett of R/20 Y16 B10 G/40, according to Croft Weaver tartan design software this has a thread count of 112 which when written out longhand is, R20 Y16 B10 G40 B10 Y16

This to me is not a complete repeat. I would have thought to be a complete repeat; i.e a mirror image about the pivots , the sett would have to include R20 twice; R20 Y16 B10 G40 B10 Y16 R20, which gives a thread count of 132.

What am I not getting?