Coffee

So I know the accepted practice for cold brew is to do a coarse grind, and to brew somewhere between 8-24 hours depending on whether you're doing it at room temperature or in the fridge.

But is this really necessary? Could I just use a finer grind and brew for less time? I'm asking because when you grind coarse, you end up having to use a lot more coffee beans (mass) than you would for the equivalent volume of any other type of coffee.

For context, I'm using a coffee sock which is just a glorified reusable coffee filter, so I don't think that grind size is going to impact filtration that much.