I worked at UPS when I was in college. Her is how it works with them.
The size of the item has NOTHING to do with how long it takes to get an item.
A package is scanned as soon as it enters the system. It is then scanned by the UPS driver as he picks the item up. When the truck goes to the center that night, it is scanned again as it is unloaded from the truck.
Packages then are sorted by zip codes and placed into a big rig truck. The item is scanned again as it gets loaded. When the truck is closed up and sealed, the TRUCK is scanned. When the hauler reaches its destination, it is scanned. As the item is unloaded from the hauler it is scanned again. 30 mins later it may be loaded onto the brown delivery trucks, it is scanned again. It is then scanned on its delivery.
When you check the status the first scan would be the origin scan.
Shipping anything in California will get delivered the next day to another part of California via normal ground delivery. Paying for next day air or 2 day is stupid in that situation.
The system for UPS is pretty good actually. Do they screw up? Sure, just like anywhere else could. There is tons of volume in really quick times, so your shit will get crushed if it isnt packed good. The guys loading boxes dont know what is inside and they are hauling *** loading those trucks. They are not gentle.