It varies, the example from the Topkapi Scroll, with the tile-like patterns of triangles and swastikas, took me a minute to recognize (but it's been 25yr since I took Arabic as an undergrad). Some of the other examples are fun, the shahada that looks like minarets is actually mirrored text, so it reads backwards from the left and normally (well, it's super-stylized) from the right.