depends on what kind of mask you using lar.
if you chill your deep cleanse mask, not nessesary lor.
but if you using moisture mask(ussualy in gel or liquid form), you
chill it is just to let the coolness soothe the skin.
and moisture mask is used with pores tighten. so, the coolness will
also act as that purpose lor.
the procedure will be the same for body.
but we usually don't do body mask at home one.
unless you kanna sunburn and need extra moisturizing.
if not just scrub and moisturize will be enough.