Much attention is directed to auspicious alignments, such as at solstices.
Is it not possible that many sites that don't appear to have such alignments nevertheless WERE aligned on the sunset/sunrise of a particular "ordinary" day, the significance of which (someone's birth, for instance) cannot be known? Wouldn't a sky-watching, calendar-aware culture be well aware the sunset moves through the year and returns to the same place next year, and make use of the fact?