Individual sites could have alignments, astronomical or to landscape features, though it'd be difficult to establish with certainty because of the bulk of the stones and their close proximity to each other.

As far as I'm aware there is no universal four poster rule of alignment, although in Southern Ireland the template seems to be a grouping of long axes parallel to a NE-SW diagonal. Imagine two stone pairs, aligned NE-SW and set side by side and indeed their form seems as close to such a mutation as to a 'traditional' four poster.