I've wondered ...
I've been to the Grand Lake Casino in Grove, OK, twice. I arrived both times before the tables opened, and on both occasions, rather than crack open new decks, etc., the pit boss opened a cabinet and pulled out an already-loaded shoe.
I've never seen this done anywhere else; and I lost heavily. Honestly, it's possible that my losses were due to normal fluctuation; but I'm not taking unnecessary chances. I haven't been back.