These days, the unit of shipping is a 20ft container. If you can't fill one, then the freight company will need you to crate the furniture and it will be packed in a container with other less than full container shipments.
It is a lot of work for all parties involved and that is why even small details matter. In some cases it is cheaper to ship using a complete container, even if you have to fill it with packing material to stop things moving around.
My family have moved quite a bit of furniture internationally and considering the costs, insurance, damage, claims, etc. Unless you are talking about very high value antiques it is not worth the time, effort and cost.
In my experience people want new, modern looking stuff. A couple of years ago I had to sell beautiful estate furniture which cost tens of thousands to buy. I only got a couple of thousand after a lot of haggling, etc. I didn't even recover the shipping costs that my family had paid decades ago.