Question: Back when I first memorized blackjack basic strategy, I learned that against a 5 or 6, I should always split 4s. But recently a friend of mine, who is a regular blackjack player and, as far as I know, plays perfect basic strategy, told me that he hits 4s. So which one of us is right, should I hit it or split it?
Actually, both of you are right, but it all comes down to where you play.
The basic strategy you learned, where you split 4s against a dealer 5 or 6, is based on a certain set of house rules. Specifically, this course of action is the best if there are multiple decks, and if you are allowed to double after splitting. If those are the rules where you play, then keep on doing what you're doing.
However, if your friend plays at a different casino where the player is not allowed to double down after splitting, then he is doing the right thing. When you split 4s, you are likely to end up with good doubling hands. But if you can't double again, then you can't maximize your winning potential against a 6. And if the dealer is showing a 5, then splitting without doubling actually turns into a losing play.
So, if you can double after splitting, feel free to split away against a 5 or 6. But if you can't, then take a normal hit against a 5 or a 6.
One other note, the above guidelines are for multi-deck blackjack games. If you're playing single-deck, then things change a bit. In the rare event that you find a good single-deck game which pays 3-2 on blackjacks, then you should absolutely play, but you'll have to change your splitting 4s strategy.
In single-deck, if you can double after splitting, then split against not only a dealer 5 and 6, but also against a dealer 4. But if you can't double after splitting, then instead of taking a regular hit, you should actually double down against a 5 or a 6 and hit everything else.
