If youv'e got Zbrush then I suppose you dont need to bother BUT, I think its very good practice to UV map, for example, using AUV tiles is a pain to alter in PS if needed, or indeed add spec maps, SSS maps based of the primary colour, etc etc as they make no sense at all as they dont care about the layout, making understanding what your looking at really hard and almose impossible to alter manually if needed.

Also you could paint a displacement map or a bump in PS to get subtle maps that say your comp may not be able to handle in Z. Or even model in the detials (large wrinkles etc), in maya giving you a basis to pait the bumps.

I wouldnt go along thinking that using Z lets you get away without doing some hard work, to get the best out of it you need to have an understanding of the workflows associated using traditional methods otherwise your not getting the most out if it or your time.