It's wild how much curricula within high schools must differ, because my school went out of its way to teach and encourage/require its use on nearly every quiz and exam. We joked sometimes class felt more like calculator class than math class. This was Texas, too, which I hardly consider a pioneer in education. Maybe TI pride?

Now that I think about it, this could have been a strategy my high school drilled into us as a way to increase SAT scores, since TI-84s were allowed to be used there.