Fairly Self-Evident


K 8 4
5 4
A K Q 9
A K 9 7
J 9 7 6
K 10 9 6 3 Q 8 2
5 3 2 J 8 7 6 4
Q J 10 8 5 4
A Q 10 5 3 2
A J 7 Contract: 7 spades
10
6 3 2 Opening lead: Q of clubs

Declarer took the opening lead in dummy, ran three rounds of trump, then three rounds of diamonds, sluffing a heart and a club, cashed the A of hearts and then three more rounds of spades. The hand looked like this after 8 tricks and before the first of those three spades was cashed (three spades, one heart, one club and three diamonds):

------
5
9
A 9 7
------ ------
K 10 9 6 Q 8
------ J
J 10 8
10 5 3
J
------
6

East had already gotten down to one less club than dummy while keeping one more heart, but, hey, this is a seven bid, and clearly declarer wouldn't have the entry needed to profit from cashing the A of clubs, then ruffing out East's last club. So there's no harm in that. One trick will do the trick, eh? But on the next spade lead, as declarer sluffed his last heart from dummy, East sluffed the 8 of clubs! Why the club when dummy is showing two at that point? It's incomprehensible.
Could East have felt he was being squeezed in three suits? Perhaps. After all, he was guarding against that last diamond also. And maybe he needed a guard to the Q of hearts? But blanking the Q would cost only if declarer held the K J of hearts, meaning he could have finessed against the Q long ago. Well, it's a possibility, of course, that declarer had that holding and declined the finesse for one reason or another. Declarers don't always use their entries wisely, we know. But if push comes to shove, if the choice is between protecting a suit only you can protect and protecting a suit declarer may have made a "subtle error" in, you'd better guard the suit only you can guard and presume some competence on the part of declarer. The J of clubs hadn't fallen at that time, but if declarer has it, he had plenty of opportunity to cash it after your partner's (in that case) strange lead. No, West must hold the J of clubs -- bare. Nothing else makes sense. If he has a guard to the J, then declarer (who sluffed a club on one of the diamonds) would have started with 2 clubs, and would now have no entry to the A! And if declarer has a guard to the J, he was on claim long ago.
So-o-o-o-o East must keep the same number of both diamonds and clubs and trust that his partner can protect hearts. Sometimes you can't protect three suits and are squeezed. At other times you can't protect three suits and can turn protection for one over to partner and beat the contract. Playing after dummy, East should find no difficulty here and beat the contract. Expensive? You betcha!
Four declarers made 7 spades, while about 6 or 7 picked up 13 tricks in 6 spades. They of course had a lot less at issue in a 13th trick, so I printed out only one of those. So let me go through the other cases where 7 spades was made.
Case 2: Same opening lead, and same 3 spade tricks cashed, East discarding a club and a diamond! A club! Even before sluffing a fifth diamond? But this is a 7 bid. In a trump suit. Had declarer been dealt a doubleton club, he could now ruff the third round and establish the fourth club as a winner. East should certainly want to keep the same number of clubs as dummy shows. To be sure, declarer wasn't dealt a doubleton club, and East can live with only one guard to the 10. So that wasn't what did it. After cashing the K of clubs at trick 5, declarer came to the A of hearts and cashed three more spades. The hand looked like this before the last spade was cashed:

------
------
A K Q 9
9
------ ------
K 10 ------
5 3 2 J 8 7 6
------ 10
3
J 7
10
6

Oh, oh, oh, oh! Do you see what I see? This wasn't a foolish discard, as I had at first supposed, after having looked at Case 1. East is squeezed on that 3 of spades. Declarer discards dummy's last club and East rightly hangs onto his guard to the fourth round of diamonds, though his partner's play of the J of clubs on the second round of the suit probably told him he's being squeezed. Declarer now played the 6 of clubs, discarding the 9 of diamonds and claimed. Very well done, Ms Declarer. Very well done.
Was that squeeze open to the other declarers? Yeah, I guess it was on that opening lead, though a diamond opening would wipe out a valuable entry and kill the squeeze.
Case 3: Spade opening lead. Declarer cashes three rounds of spades, comes to the A of hearts and cashes two more spades. East discards a diamond, then a club (with four showing in dummy!), then, as declarer discards a club from dummy himself, East discards another club, keeping himself one behind dummy's number. Actually, declarer could at that point have simply cashed three club winners for his contract, though he couldn't know it, of course. But East, rightly keeping four diamonds has a fixation on that heart suit that his partner can control. Now came a diamond to dummy's hand, three honors cashed, the 9 covered by East and ruffed, declarer now going to the A K 9 of clubs and his grand slam.
Could this declarer have embarked on the same squeeze? No. He wiped out his diamond entry at trick 7, and evidently had no thought of a squeeze here. If East hadn't fixated on the hearts, I believe he would have had that declarer for 26 plus IMP's. After all, you can't guard everything, and declarer, who had led to the A of hearts and sluffed a heart from dummy on the next trump lead had indicated neither a propensity for finessing in hearts, nor saving that suit for later in case other pursuits didn't pan out. No, I think this declarer would have been a goner had East stuck to saving the suits dummy showed.
Case 4: This one is almost too bizarre to relate: back to a club opening lead, taken with the ace, five spades were run, then the 9 of diamonds, finessing the 10, East playing the 7. It's right there. Declarer claimed at that point since he can sluff two hearts and a club on the remaining diamond honors. Somebody wasn't paying attention, it would seem.
Case 5: (Defending against 6 spades). Spade opening lead, continued out to trick 5, as East sluffs the 8 then 4 of clubs, evidently telling his partner he has an even number? I dunno. The rest of hand consisted of simply cashing out top winners, though declarer couldn't have known clubs were now breaking in his favor until trick 12! Whereupon he picked up the Q of clubs and the 10 with the second round of the suit, the 9 of clubs then being his 13 trick for an overtrick.
It just seems to me a perversion of simple common sense to place informing your partner of your club holding, which information he can't use, above saving those cards to guard the fourth round of the suit which you can see dummy holds (though in fact, he only needs the third round). Hey, man, a thrice-guarded 10 is often a very valuable card. If declarer has A K Q J and can cash them all separately, then the 10 might as well be the 5. But if any trick picks up two honors, whether one from your partner and one from declarer, or declarer overtakes an honor, spending two on one trick for whatever reason, that 10 is going to stand up.