I believe it's better to have many small stockpiles. But you shouldn't put it near labourers. It should be placed near where the recurring production is- trading posts, quarries, foresters/woodcutters. You want these people to store their resource output as quickly as possible so they will go back to working and producing. Some stuff like firewood, you do not want your villagers walking out into a blizzard because they're freezing and need firewood but the stockpile is far away. I apply the same principle to storage barns.
The real problem is for resources that you can't reliably produce locally like iron or stone. For these resources they will have to walk a long way to get it from whatever your current source is, and there's no stock pile placement to alleviate this. But you can place your stockpiles to increase production. It's a lot easier to build more blacksmiths than to summon more merchants to get more iron.