Even if they are nominal that means they will all be less than the size mentioned in the docs (ex: not 6 but 5" 3/4" So if all the tiles have the same deviation (1/4) from the nominal size the problem remains the same but with different numbers

You probably want to stick to a pattern that is shown on the manufacturer website of the pavers you buy. You know they have tested those patterns and they work. If you make up your own pattern or get it from somewhere else, then no guarantees it will fit right.

the above are from a manufacturer site, see here https://digitalassets.daltile.com/content/dam/Daltile/website/resources/products/pattern-guides/interlocked.pdf

IMO choose a less complicated pattern

I am starring at these https://www.stone-link.com/resources.html My stone is Eramosa flagstone and I have a 88x74.50 porch to put flagstone on. The suppliers is giving me these sizes 30 x 24 , 18 x 30, 12x 24, 12 x 18 and I can't seem to do better than this. Trying to use large slabs doubles the shopping list. I need like 78sq of slabs (9 pairs of the 2 sizes used below) to cover what is 46sqf of porch area ...that sucks

the red contour is the porch area, door at the north access at the south of the picture. Left and right wall and respective concrete planter