See what happens to West in today’s deal if East gives the defense against four spades insufficient thought.
Declarer takes the heart king lead in dummy and draws two rounds of trumps, ending in hand, before playing a diamond up. West may play small in case East holds the jack (or the queen, where declarer might have a king-jack guess), but this would cost the contract. Declarer goes up with the diamond king and subsequently works on clubs, leading twice up to dummy’s honors to lose only two tricks in that suit.
It could be argued that West should be suspicious as to why declarer started on diamonds instead of clubs, dummy’s longer suit, but the fault lies with East, who has both minors under control. East can see there is nothing to gain by ducking the first diamond, so he should seize the opportunity to discard the diamond queen at trick three! Now West knows ducking the diamond is futile. He should take the first diamond and cash a heart, and sound defense should defeat the contract from there, West taking care to win the club ace on the first round lest he be endplayed with it later on.
Declarer could make life that much harder for the defense by drawing only one round of trumps before playing a diamond. This is his best strategy in that it gives East no chance to make his enlightening discard, though most declarers would not tackle a key suit without drawing the final trump unless they had no decision to make — in which case West might decide to take the diamond ace anyway.