As you probably already know, there is no size restriction for the Pottery Barn account. My guess then is, UPS is making some money from PB, unlike Dell with their 3 delivery attempts.
I, too, hate Pottery Barn. If you end up with an eight foot by five foot package on your car one day you are screwed. You can't make it your first stop because it won't fit through the bulk head, and you can't get it out the back because you are so bulked out on your normal RDR, RDL, and RDC stops. Now you have to sqeeze your body around this oversized package just to get to your airs and after that your squeezing through to get your 1000 and 2000 sections off.
Do we get a time allowance element called "climbing over pottery barn volume"? I think not. Just another element the UPS driver is getting screwed in time allowances.