Six clubs looks pretty safe even with a spade attack. I had unfortunately focussed on a spade slam and when I went back to determine how declarers had fared in 6 clubs, the hand was gone. Six spades? That should be in deep trouble on a heart lead. Declarer obviously cannot get a sluff on the long clubs until trump are out and has to allow a trick to the ace of spades.
But what's this? One declarer did get a heart lead and did make six spades? How so? Well, lemme put it this way. Two declarers got a heart opening lead and were able to win a trick with the jack of spades, and then ruff out the ace of diamonds setting up the queen. One then went on to make his contract as just mentioned while the other went down. How come he went down?
Well, because after taking the opening lead with the ace, he cashed his A K of clubs! I'll never understand it if I live to be a 100. What purpose was served by cashing the A K of clubs? They're both in the hand where he was and a 3-1 club split would itself have queered the contract. It's just baffling. Anyway, when the jack of spades held, he ruffed out the ace of diamonds, establishing a very good diamond in dummy, to which he had no access.
In any event, I have repeatedly said Don't cash out top winners without some reason until such time as you're ready to cash out all winners. I call it doing your housekeeping. When dummy comes down, you want to see what you have to do to maximize your winners before you start cashing top cards. You might want to use a top card to shift the lead from one hand to the other, lose a trick in a side suit to get a subsequent ruff in the short hand, run a suit headed by A K 2 in dummy opposite Q 3 in the closed hand so as to get a sluff of a loser just uncovered. Oh, there are reasons and reasons. But if you don't have one, why cash top winners when you've got housekeeping to do?
Look at the task before you and get on with it. Here it would have been a lucky break to get that jack of spades past West if only declarer hadn't cashed his clubs. Now a low club to the Q and he's in clover.