I don’t think they use tiles at all
components can load/unload just the same.
Either way, tile size doesn’t matter. What matters is how many tris are in your lod0 components because you can potentially Activete 4 components at once and cause a x4 load stress on the system via near useless increase of tris count.
if to that you add tessellation (even distance based) you’ll have several areas with sub 1cm quads being subdivided - causing floating point stress on calculations for absolutely no good reason (other than someone decided the landscape mip system was supposed to work that way).
Depending what you have in the scene, pick a tile size that’s comfortable enough to allow you to work (8km for 100km^2+ is a must) and live with the limitation and having to balance LOD 0 out for performance.