For hair wash, yes, the hairdresser recommends just finishing with cool water to close those pores off.

For overall contrastive showers, if you can manage alternating, it gives an immense satisfaction, probably due to adrenaline and endorphine, and trains the vasculature (as the blood vessels respond in opposite directions to hot and cold). It is also believed to improve stress response and immune response. I have also read that it helps with the surface skin cell turnover but have not verified it.