This is the whole reason we teach picking out your best landing field and following the proper steps before landing... A private pilot (lower time that is), is not going to have the experience or muscle memory to be able to complete a restart memory checklist at 500ft agl. You need to teach them decision making so that they know the only thing they should be concerned with at this point is finding a good place to land IN FRONT of them, or BARELY off to the side. You have to remember that as a CFI we hold quite a bit of responsibility, and you want to give your students the BEST tools to keep them safe and responsible.