Inspired by the discussion here: https://www.ravelry.com/discuss/woolly-thoughts/4250771/26-50#44 - this is one possible way of handling the Z curve visible in the edges of the middle tile
Shown with a cast-on count of 4 stitches.
1 2 3 4 5 Horizontal repeats
1 2 3 4 5 Vertical repeats