Why do you think that the micas flat minerals in these rocks are all parallel or sub-parallel to one another?

The parallel or sub-parallel orientation of mica minerals in rocks is primarily due to the processes of metamorphism and deformation. During these processes, the minerals experience directional pressure, causing them to realign along the same plane to minimize stress. This preferred orientation enhances the rock's foliation, allowing the micas to exhibit their characteristic shiny appearance and layered structure. Additionally, the platy shape of mica crystals naturally lends itself to this parallel alignment under such conditions.