I work at a UPS hub, so I'll try and shed some light on this (side-note; I've only been there 10 months, so I'm not 100% sure on some hub operations).
At the hub where I work, there's a UPS Customer Center located right next to the main UPS hub. Basically, if a customer would like to hold their package for pickup, the loaders at the hub will get a loud, beeping message on their scanners that reads "INTERCEPT" as soon as they scan the package. This means that the customer wants the package to be held for pickup, so the loaders take the package out of the trailer and a "sweeper" comes by and grabs the package. From there, I'm not really sure what happens, but it gets transferred over to the Customer Center next door.
In theory, you may be correct in saying that having it shipped to a different UPS Store would delay pickup, because I'm assuming that would mean a UPS driver would have to deliver the package to that specific UPS Store, rather than just having the hub employees transfer it to the Customer Center next door. Now, I'm not sure how other UPS hubs are setup, so there may not be a Customer Center next to the main UPS hub.
Also, 128 GB Space Gray AT&T iPhone 6s in "Processing Items" currently.