Would this do what you are looking for?
Greenville, NC with grooves.skp
What I’ve done is make a tile out of one of the small rectangles in your wall. Then use the Offset tool to offset its perimeter inwards by 10mm. (or whatever size of ‘score line’ you need).
Then connect the inner and outer rectangles by diagonals at the corners, select the inner rectangle by a double click, then Move the face outwards by half the offset - 5mm in this case.
Make this into a Tile component, then array it using the Move/Copy tool over the face - 15x horizontally and five times vertically.
That gets you ‘score lines’ between the tiles.
Your tiles aren’t any particular size in either imperial or metric units. Is that right? About ~2’11 1/2 horizontally, or ~901.7 mm
If you use an awful lot of these tiles, your model may bog down with so many edges. If so, render one wall, then use a screen grab to get an image to make into a tile-sized texture you could apply, instead of drawing and shading all the grooves.