I believe it’s generally not correct to split 5s in blackjack. Two 5s make a total of 10, which is a strong starting point for doubling down, offering a good chance of drawing a high card. Splitting 5s would leave you with two weaker hands of 5, putting you at a disadvantage. Instead, it’s usually better to double down with a 10 when the dealer has a weaker upcard, maximizing your chances of winning with one strong hand rather than splitting into two weaker ones.