I'm not going to address the question of whether 1/2" is too narrow to cut next to the fence. That's another discussion. For myself, I have no problem cutting 1/2" between fence and blade when proper precautions are taken...
So, to answer your question, if I need a 11 1/2" board I set my fence to 11 1/2". If I need a 1/2" strip, I set the fence to 1/2"