I don't know if this is a pattern, but for my last three orders from Target, I selected the option to require a signature upon delivery and each order was shipped UPS. I ordered one yesterday and it has shipped and will arrive Friday. This is a lot faster (for me anyways) than when I did not request the signature.
I had the same experience. I ordered on Friday evening and the cards arrived Wednesday. If I hadn't ordered at the start of the weekend, it probably would have shipped out faster. My daughter's last order without the signature took almost two weeks.
I really like the added security of the required signature, and the fast shipping is an extra perk! I did notice that the cards went solely thru UPS rather than being handed over to USPS for final delivery. That's probably why it moved so quickly.