How long did it take to actually gather all the dead from a really big battle with a really big number of dead? (500 B.C to 1400 A.D)

by AlphaCodeNumerial

Example, battle of Cannae.

mightjustbearobot

Add on question, if I may:

How did defeated enemies collect their dead? Were they always piled into a mass grave and just buried without honors or was it like in the movies where they allowed the opposing side to come and collect?