The strategy and practice of wood procurement varies depending on the type of mill that will ultimately consume the wood raw materials. Most active mills in the US South are either producing pulp and paper or lumber, yet their fiber needs (and thus their supply chains) are quite different.
Pulp and paper mills primarily focus on purchasing fiber for the lowest price possible, as the size of the material they consume is not a real concern since they can chip almost any size tree and make pulp out of it. There are really only two principle directives for procuring wood for a pulp and paper mill: 1) never, under any circumstance, allow the mill to run out of raw material, and 2) purchase that raw material at the cheapest price possible.
Sawmills generally have the same concerns. They too focus on buying enough wood to log the mill while meeting production quotas and buying it at the least expensive price possible.