Common Sense?

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K Q 7 5
A K 8 5 4 3
J 6 3
Q 10 8 7 6 4 3 2 J 5
J 8 6 3
------ Q J 9 7 6 2
Q 9 8 7 10 4
A K 9
A 10 9 4 2
10 Contract: 7 hearts
A K 5 2 Opening lead: ?

This hand bedevilled the be-jesus out of me for the better part of a day. My original title was Common Sense, the question mark now mocking my early belief that the hand depended on plain old horse sense, as opposed to hands that can be made on a totally improbable play (see this hand) requiring a vision improbably accurate. I will start with my original assessment and then go to what gave me grave doubts.
Thirteen people were in grand slam here. Only five made it, and of those five, three got a club lead, one of those leads being the queen (!) wherein declarer could hardly go wrong. So it would seem that only two declarers made the grand on their own steam.
If trump split 2-2, the hand is a laydown, and the veriest novice will come out the same as you. But trump don't figure to split 2-2 (the odds favor 3-1) and even if the odds did make 2-2 the slight favorite, you don't want to bank everything on that if you've got a reasonable chance elsewhere. Hence:
First of all, the people who took three rounds of trump simply threw away their chances. They can only ruff once in dummy now. The only thing that could have saved them at that point would have been the queen of clubs falling short, and you don't want to bank on that do you for such a magnificent contract? Actually, there was another possibility from declarer's viewpoint, to wit a 3-3 diamond split, but we can see that neither possibility would pan out. So you don't want to take three rounds of trump and then pause for thought. What I find a little puzzling is that those who ran those three rounds got the jack of hearts on the first round and so could see that trump weren't likely to split 2-2, and that they could ruff how many cards high? Aye. Therein lies the rub.
The hand is a bit tricky (as opposed to what I said in my first draft). It's first of all highly dependent on whether the first round of trump is taken with the ace or an honor in dummy. If the former, declarer can see that he can ruff twice with dummy's honors, though even there re-entry can be a bit tricky. Declarer can run two spades, sluffing two clubs, ruff a spade high (yes, East can sluff a club), back to the A of clubs, ruff a club high, and back with dummy's last trump. A little more dangerously, I would say, declarer can sluff two clubs on the spades, cash the A of clubs, ruff a club high, back on a trump lead, ruff a spade high, then back on. . . Well, you can only do it cashing the top two diamonds! But it works! the improbable distribution in spades making the hand short in trump even shorter in diamonds!
On the other hand, those who started leading out trump by going to one of dummy's honors have an even trickier situation. They can ruff only one black card high, and who'd suppose that East would have only two spades! Actually, through the luxury of hindsight, we can see that a couple of ways work to get two black cards ruffed (a third to go on the second diamond honor). But -- in contradistinction to those who simply ran three rounds of trump -- I certainly wouldn't critique the declarer who guessed wrong on ruffing a spade low, thinking it made more sense to save the high trump for the clubs. Anyway. here is one way: Cash one round of spades, sluffing a club, ruff a spade low, back on club lead, take a second round of clubs, ruff a club high, back on a trump lead, draw trump and claim, with a second diamond honor to sluff a club later.
Or, alternatively, cash two rounds of spades, sluffing two clubs, cash the A of clubs, ruff a club, low, back on a trump lead, ruff either a club or spade high. Now you've just gotta get back to the closed hand, not forgetting to make use of your second diamond honor. Hm-m-mm, this looks a little more dangerous, but through the luck of the Irish, the hand short in diamonds has no more trump.
Still, even recognizing that that line favored by the odds (ruffing the third round of spades low) doesn't work, no declarers went down by that line and the two ways they did go down indicated a lack of, well, common sense, as postulated from the start. Five of the 8 simply took three rounds of trump as soon as they got the lead. I have acknowledged above two ways they might have come out smelling like a rose (the queen of clubs dropping short, 3-3 diamonds), but those are both long shots, and clearly declarers, unless they like long shots, weren't thinking of how to take care of three little black cards in the closed hand, that is, how to take care of all of 'em, since they were in the grand.
The other way declarers went down, three of 'em, was look to dummy for ruffs, understandably, but to ruff the third round of clubs low (one having been thrown on a spade) and get overruffed. You've got to be very suspicious about that third round of clubs, since a 4-2 split is the likeliest. In hearts, you have both the chance of a 2-2 split and the jack falling stiff, so to use a high trump for the third round of clubs is just about mandatory. Diamonds, of course, should not be touched until you're finished with everything else. The opening leader can't lead them, and since you're in a grand, you don't expect to give an opponent the chance to lead them.
Far from seeing this hand as a matter of common sense (and I can't understand why I once did), I think it requires a combination of good play and plain old luck. But the one thing I haven't changed my mind on is that the declarers who ran three rounds of trump deserved to go down. That wasn't bad luck. It was bad bridge.

Incidentally, two of the 8 who went down got a club opening lead and declined to test the jack. I looked up the self-appraisal of some who went down, either by running three rounds of trump or by testing the safety of a low ruff on the third round of clubs. One offered a delightfully ambiguous "advancing". Another said "advanced". But the one I liked best was "advanced ++++". This declarer was one of two who got a club opening lead and declined to try the jack. Okay, he can still make it by a line suggested above, and particularly when he sees the jack fall on the first round of trump and knows he can ruff a club high. But he proceeded to cash three heart tricks and now he can't get two ruffs in dummy. It makes no sense. Advanced plus, plus, plus plus? I don't know why he doesn't dispense with this modesty and call himself an expert.