Bill Tindall, E.Tn.
I have seen some highly automated mills that automate various steps of the lumber production process but I have never seen a system to sort boards by width, nor any reason I can fathom to do so. If a mill is gang sawing cants there will be a lot of 6, 7 or 8" lumber in the upper grades, depending on the cant and capacity of the gang saw.

That said, after drying there are mills that supply specific products from their KD inventory. For example, Baillie told me they have about 60 oak products, by grade and dimension. A retailer would not be ordering direct from Baillie. There would be a distributor in between retail and manufacture. I suppose a distributor could order a pack (this would be 1000 bdft+/- of some approximate width of oak) but I don't know what the motivation would be to do so.