Strange Deck Amounts

As far as I can tell, shoe games like blackjack, baccarat, and casino war are usually played with either six or eight decks, though single, double, and triple deck blackjack seem to exist.

I noticed that in the Massachusetts rules for Casino War, 7-deck Casino War is allowed, but this is not true in California or Maryland. In the Nevada, Down Under Blackjack is allowed with either 2, 4, 5, 6, or 8 decks.

My question is, why do some states allow or prohibit what seem like arbitrary numbers of decks? Why would a casino choose to use a non-standard number like five or seven decks?

Gracias

One of the casinos near me deals (or maybe dealt - it's been a minute) a 5 deck blackjack game.

I believe they told people it was because the fewer decks slightly helped the player.

In reality, they didn't cut any less off the back than neighboring casinos, so the percentage penetration was worse, and the dealers were happy to encourage "good luck" tokes on the first hand after every shuffle.

Spanish 21 is often played with 5 decks, especially in casinos in Washington when I used to play.

I imagine the player advantaged gained by 6-deck vs 5-deck blackjack is about equal to the casino's cost of buying slightly less decks.

Quote: harris

I imagine the player advantaged gained by 6-deck vs 5-deck blackjack is about equal to the casino's cost of buying slightly less decks.
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I think they'd need to see around $16000 wagered before the cards were changed out to balance the cost of one saved deck.

I think it was a $3 table, and the largest cheque in the house was $100.