When I first looked at the hand (knowing declarers had made 4, 5 and 6 on it), I figured declarer should lose a heart, a diamond and a club -- and looked to see how defenders had allowed those extra tricks. Sometimes I'm surprised by a squeeze and sometimes there are other plays that escaped my cursory look, as happened here. For declarer here has indeed a play for plus 5 on that Q of hearts lead. The 9 and 8 look awfully appealing when the Q, K, A and 10 all go on trick one! Declarer makes five, of course, sluffing a diamond on the 9, letting West have it with the J, a loser he always has anyway, and then using the 8 to sluff a club.
To be sure, you don't really know you're gaining by sluffing a club. When you're missing the K 10 9 8 7 in a 3-3 suit and hold a J or Q is opposite the ace, you'll probably (though not necessarily) have a loser in the suit regardless of where the K lies. The problem is, you don't know if you have a first-round loser on an offsides king or a third-round on an onsides cover of an honor. Obviously it wouldn't help declarer any to sluff a club if he's got a first-round loser. But then, he isn't hurt letting West capture his low diamond with his last heart honor and may be helped by an onsides king and the value of sluffing a club to avoid the third round. And he would have been.
Some declarers were missing that, covering the Q, then ruffing the heart continuation. Well, you've always got a diamond loser, man. Why not discard that -- and look at what you have left? Which is the highest danged heart left in play! Even if it is only the 9. Another declarer kicked away his chance by not covering the Q. A continuation would presumably have been covered, allowing declarer the high heart on which to sluff a diamond, which is just as good as covering the first round as outlined. The problem was that West now shifted to a diamond, and declarer can't promote a heart winner on his own.
But the category here is keeping the same number as dummy (not an inviolate rule, but like second hand low, etc., a good idea to be abandoned only for a positive reason). And it was a little interesting because defenders on both sides of the table abandoned that maxim at their cost.
Here's a declarer making six: A diamond opening lead, the J, taken by the ace, three rounds of trump then being run. The 10 of hearts is covered successively by the J, K and A. Declarer ruffs the heart continuation! I mean, this is the one who makes six, now, so the defense must have screwed up royally when declarer missed that opportunity. And did. A low club now brought the K from West! It's hard to understand. You'd think a novice would know better than to give up the king without a fight, particularly when I think of how many average players are loathe to give up their king on a (necessary) cover. Here West gets nothing. Well, that allows declarer to escape a club loser, but what about the diamond? And the answer is . . . that though East doesn't hold the high heart and couldn't use the one he has unless he gets the lead (declarer had ruffed out dummy's last heart) and that the only way to get the lead lay in diamonds and that his partner's J of diamonds opening lead gave East the Q 9 tenace over the 10 which he should have been watching from trick 1, he sluffed a diamond on the last round of trump and then another diamond on the third round of clubs! -- all this to hold onto that danged 7 of hearts -- and the 3 of diamonds won declarer his 12th trick.
Now from the other side of the table: A double violation of that maxim. Opening lead the Q of hearts, covered and won by East and a heart continuation was ruffed by declarer. So he missed a chance to develop an 11th winner and could easily have been held to 10. Three rounds of trump, three rounds of diamonds, losing the third to East, of course, who continues with the Q which declarer ruffs. On those last two rounds of diamonds, West sluffs two clubs. Now on a low club lead, holding K 10, West chooses to go up with the K. Others had given up the K easily as mentioned above, but declarer can pick up the club suit on his own when West gets down to K 10, though we'll never know if he would have. Anyway, that was trick 10. At the end of 9 tricks, West had saved the J 7 of hearts in order to get down to K 10 of clubs! Dummy was then showing one heart and three clubs!
Yikes! I just realized that declarer had a squeeze there! Or would have had had West held three clubs and a heart at the end of trick 9. The record ends at trick 10. I looked to see if declarer had played the 7 of spades, and he had not. So he had three clubs and the last trump opposite three clubs and the 9 of hearts. Had West kept the same number of cards in each suit as dummy, declarer would have had him squeezed on the last trump! Well, I'm always coming across surprises like that. Whether he would have found that if West had held the same number of hearts and clubs as dummy is unlikely, which I say in view of his failure to use the 9 and 8 of hearts.
In any event, West would have done well to keep the same number of both hearts and clubs as dummy was showing. Let declarer find his chancy winners and congratulate him when he does. But you don't want to make those winners easy for him.