Dumb Question .. but

How is a casino edge affected if there is one deck of cards used or just a single deck?

eg

3 Card Poker uses one deck in the casino. If the casino were to use a 6 deck continuous shuffler, how would this alter the casino edge?

Similarly, the difference of a casino using a single deck or 6 card shuffler with Blackjack?

My initial thoughts are it doesn't change anything. I am not a mathematician so clearly my thoughts don't mean squat.

I would like to hear from those who are into the math

I just analyzed the Pairplus bet for Three Card Poker for multiple decks. I based it on "Pay Table 7" from the WOO page because it says it is the most common. Just adding one more deck makes it advantageous to the player. If that bet were played with six decks, it would have an 8.93% player advantage. Most hands become more common; for example three of a kind (2.53% occurrence with one deck vs. 5.28% with six) and flushes (4.96% with one deck vs. 5.84% for six). Interestingly, straights and straight flushes become rarer because they need a set of cards in a narrow range which more decks makes harder by diluting the shoe with copies of cards already drawn For example, regular straights occur 3.26% in one deck but 3.10% for six. That is not enough to offset the benefits from the other hands though. Because multiple decks are so powerful for Pairplus, the TriLux side bet for blackjack, based on Pairplus, does not pay out for a pair to keep the return in the house's favor. I'd share my analysis but it is in an Excel sheet and it won't let me make a link to my Google Drive.

Pairs would also be more common with multiple decks. But most poker players would freak to get the identical card twice in their hands.

The player's optimal basic strategy would change to a higher threshold for Bet rather than Fold.

I would think they could have to adjust the pay table with trips being more common and straight and flush harder to come by
I have seen on double deck blackjack the 21+3 bet doesn't pay out as often due to only being 2 decks