Blackjack Strategy When Splitting a Pair of Sevens
Split: When the dealer is showing 2, 3, 4, 5, 6 or 7
Hit: When the dealer has anything else.
Why to split a pair of sevens
There is a good chance that that 7 will turn into 17, which is a good hand. Even if the dealer were to get a 17, the bet would still be pushed in a tie. When the dealer has cards less than 7 showing, you have an odds advantage of the dealer going bust after a few consecutive tens being drawn. The basic strategy assumes that any drawn card will be a 10 due to the high volume of 10's in the shoe.
Why to hit on a pair of seven
Basically when the dealer has an 8, 9, 10 or 11 showing, then it's likely that a ten will be drawn along with that to score higher than 17 if you were to split it. The good strategy in this case is to just hit your pair of 7's (totalling 18) and hope to beat the potential 18 or higher that the dealer may have. Mathematically this is the best choice of strategy to use in this case.