Mark Twain said, "It is a good idea to obey all the rules when you're young, just so you'll have the strength to break them when you're old."
That vaguely applies to this deal. South is in six spades. How would the play of a neophyte compare with that of a wizened veteran?
East had a textbook opening vulnerable pre-empt with a strong seven-card suit. South had an easy overcall, although he could well have had a weaker hand. So, when North cue-bid four diamonds to say that he had a strong spade raise, South happily launched (Roman Key Card) Blackwood.
South's only problem is avoiding two trump losers. If the opponents had maintained a respectful silence, the normal play would be to cash dummy's ace, then to play low to the jack. This would succeed some 87.6 percent of the time. A tyro would adopt that plan and go down here when East turned up with a low singleton in spades.
An expert considers the empty spaces, the cards each defender has outside of diamonds. West has 11 and East only six. So, East's being short in spades would be no surprise. Assuming that diamonds are 2=7, the probability of only one loser by cashing the spade ace and leading a second round drops to 73.3 percent. Is there something better?
Of course there is! South should cross to his hand with a heart and lead the spade jack. This line works whenever spades are 3-2, or West has queen-fourth, or (admittedly unlikely) West has a singleton 10 or queen. This increases the chances to some 84.5 percent.