I think we are talking about different things. Typical saunas are the neighbourhood saunas, Kietz-Saunas. They do not have any separation. Not in dressing rooms, showers, nor in sauna areas. It's all mixed, except usually a women only day once a week.
Saunas in public pools etc may have different arrangements.
Showers within the sauna area are usually mixed. Showers within the dressing areas are not.