As I said in my post to "The Punishment Must Fit…” thread, in girls schools it was used in cases where, according to you, it would be unlikely even to work with boys. In boys’ schools, it was used in cases were it was most likely to work. It’s wouldn’t be surprising if appeared to be ineffective with girls – for that reason. If it had been used on girl the same as it was on boys, it might have proved just as effective – and vice versa.
Untrue – contrary to the protestations of certain people, teachers have long understood that misbehaviour among girls is typically (though not universally) less prevalent than among boys. There is, frankly, virtually nothing in educational or psychological research to contradict this, however much it doesn’t match some people’s views of the world as they wish it was. Girls have tended to both misbehave more and been punished more severely and readily when they did so – than boys.