I used to be a truck driver and from time to time we would carry overflow for ups. We would back up to a dock at a terminal and they would use a roller conveyer to start shoving packages. A guy in the trailer would grab the package and just chunk them to the back pilling them to the celing, no stacking here. It didn't matter the size, fragile or not. There were tires chunked on top of the packages. Imagine taking a tire and throwing it 20 feet onto your box of 5ers from cbid. After the loading was done we would close the trailer hoping none of the packages came rolling out. When we got to our destination they would send a person out just to pick up the packages that fall out when the doors are opened, always about 20 packages.
I have a friend who works for usps. I can't say how the packages are handled before you pick them up but they are in large stacked cartons then rolled onto the truck. After I saw the way ups, and fedex was the same, destroy packages I started using usps.
edit: I ment to add that I ordered a $450 Titleist driver that was shipped ups. When I recieved it the shaft was broken in two places. I mean broken all the way through. Now I don't know how many of you have gotten mad on the tee box and tried to break your graphite shafted driver over your knee, but it aint easy. PS that is the reason I bought the new driver.
My c bid orders always ship on thursday and I recieve them in Arkansas on saturday.