A lot of valves prior to the 40s were quixotic. Some used oddball keys to operate and many, as noted, lacked stops and any clear indication of valve position. One I came across, quite a well built unit in what looked like solid bronze, had a recessed square-head that made using anything but the specific key made for it difficult.

Generally the modern valves have stops and a handle, or the operating head, that indicated condition. It is parallel to the supply pipes when on and perpendicular to them when off.