Unless a designer is working in a bigger organisation where roles may be very much divided and specialised, then the designer also needs to be an artworker. A good visual for a logo, a brochure layout or web page (just to mention a few things a designer gets involved in) won't – or shouldn't – see the light of day unless it has been art worked properly for the necessary media, online or printed. That means final press-ready files for the printers or screen-ready for online or interactive use.