are you referring to fiber or rc papers? If its RC, then you don't have to wash for hours, like some people do. For RC I generally do about 15min for a final print, 5min for a work print. for fiber, I wash for 2-3hrs. I just like to make sure that ALL the residual fixer, and hypo, selenium or other toners are COMPLETELY out of the print.
and being that fiber is FIBERS, not a coated piece of plastic( like rc and color(rc paper too) prints are. Even with color prints, I like to re-wash them for 5-10min after they've gone through the processor. Water is at 70F.
-Dan