A good way to shuffle large decks in my opinion is to get some sleeves an den learn to Mash Shuffle. Here is a video about this on YouTube. Depending on the form factor of your cards it may be tricky to get fitting sleeves, but if you do it’s very much a game changer.
“Many were increasingly of the opinion that they’d all made a big mistake in coming down from the trees in the first place. And some said that even the trees had been a bad move, and that no one should ever have left the oceans.” ― Douglas Adams