I think that war arrows at least have to be considered a one shot item. You will almost assuredly get a large percentage of the shafts back but you cannot depend on it. Hunting arrows may be another thing entirely.
I'm also leery about the comments regarding infection and dirty heads. We with our modern knowledge know that dirty heads will cause infection but germ theory is not known when the war bow is in use.
So while archers put their arrows in the ground I don't think the purpose was to increase the chances of infection, that's merely an unintended and unknown side effect. IMHO ;-)