A Balanced Major Disregarded?

A
A Q 5 2
A Q J 8 5 3
6 3
K Q 9 10 8 6 4 3 2
7 4 10 9 3
9 7 10 4
A Q 10 8 7 2 5 4
J 7 5
K J 8 6
K 6 2 Contract: 6 dia, 6 hts
K J 9 Opening lead: 4 of hearts (against hrts)

Only four people bid this slam, and only two made it! -- a rather low percentage, given that totally unmakable slams often draw that proportion of slam bidders. Anyway, first to the diamond slam. Played from the North hand above, a club lead scuttled that contract. But it didn't matter what the opening lead was! On this unbalanced suit, you've got eleven winners only. Opening leader could have closed his eyes and led without harm. (It is the same in no trump, by the bye. There is no ruffing power in diamonds, and all suits are stopped, so it's going to play the same way. You run 11 tricks and out.)
In hearts, well, it is self-evident that you can get a fifth heart winner simply by ruffing a spade in dummy. This should be easy to manage even on a 4-1 split. Sometimes you won't find any advantage in the balanced 4-4 fit when it splits 4-1 because you can't get the sluffs you want until trump are out and at that time it doesn't do you any good. But here, one should be able to maneuver a spade ruff with impunity. Indeed, I would consider it a wise precaution to cash the ace of spade early and end up in the closed hand on the second round of trump so that you can take that ruff if the suit splits 4-1, then ruff low, cash the last honor, return to the closed hand with the king of diamonds and draw the last trump.
So how did somebody go down in 6 hearts? Well, here's how. Opening lead a heart to the jack, now two more rounds of trump are drawn, diamonds run, declarer sluffing two spades and the jack of clubs. Two spades and the jack of clubs! That jack of clubs epitomizes the rather scattered thinking here. "Maybe if I throw the jack of clubs (keeping the 9, heh-heh-heh), I'll confuse the opponents into giving me a trick?" When he had sufficient winners right before his eyes!
The 5 of spades is substantially a winner. The five of spades? Well, of course the actual winner is a ruff in dummy, but you can't ruff in dummy, using the last two trump separately, unless you have a card to ruff. So if the 5 of spades isn't fated to win a trick on this hand, it'll have the effect of producing one, the 12th winner, which wouldn't be possible if, say, declarer had a singleton spade in the closed hand and five clubs. And that should be recognized. . especially in a six bid. The last trick, by the way, consisted of the K and 8 of hearts taking care of the king of spades. You don't want the K and 8 of hearts to go on the same trick, now, do you?
There was one other misplay, this time to allow an overtrick, where declarer did sluff his clubs. It involved a matter I've taken up before: Keep the same number of cards in any suit as dummy has when you can conveniently do so. A little ironically, I've just about always referred to a four-card suit in this regard. But here, it's two ittle-bitty clubs that wound up becoming important, the 6 actually taking the last trick! West sluffed all his clubs but the ace, as he watched declarer sluff his 9, J and king. A club ruff now wiped out the ace and on a ruff of a spade, the 6 of clubs was it! East couldn't guard the suit because his highest club was the 5! West should certainly retain two clubs, getting down to a lone spade honor.
Declarer now ruffs a club and ruffs out the queen of spades, but he can't get back to the closed hand to use the jack, of course, and West gets the last trick.
[That's what I wrote years ago. In coming back, I decided to look at West's situation a little closer. For indeed, he's also the only defender who can guard the J of spades. After 10 tricks (six diamonds, sluffing 3 clubs, three hearts and the A of spades), declarer has a trump in each hand with two clubs in dummy and two spades in the closed hand. West would seem to need two cards in each suit, which he cannot do with three cards left. Is West therefore squeezed?
No, he isn't really, though it would seem so and it is ticklish. But it's a matter of where declarer winds up with that tenth trick, which would have to be dummy, since he has to take a third round of trump before running diamonds. And if he is in dummy, he can ruff a club and get back to dummy on a spade ruff, but he can't ruff a spade and get back to the closed hand. (If the A of spades were in the closed hand, not knocked out on opening lead, declarer could finish 10 tricks in either hand. And if in the closed hand at the end of trick 10, then West must keep two spades and one club.) So West is not squeezed, and should get down to a single spade to protect against . . . protect against . . . the 6 of clubs! It's rather amazing that those mighty club honors must guard against the 6 of clubs, while a mighty spade honor must be discarded at trick 10. But that's the way it is.