It simply realigns into 0.0625 studs every time the plot is loaded, up to 0.005 stud tolerance that causes pixel gaps.
It only applies to orthogonally aligned parts (tolerance 0.01 degrees), not rotated parts.
This simple feature that prevents pixel gaps to be formed, and in building gui there'a Realign button that realigns to nearest 0.0625 stud grid point.
and the 