One or De Other

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

When I saw that declarer had been allowed to make his contract here when he surely should have to lose two trump tricks, my first thought was, "Oh, no. Don't tell me East covered the J of spades!" Well, as it turned out, East didn't cover that J of spades. The culprit was West on two successive, totally sense plays.
Declarer won the opening heart lead, cash two rounds of clubs to discard a heart, of course, and then led the J of spades -- which held! Wait! That's not all. Declarer now ruffed a heart and led the 10 of spades -- on which West went up with the Ace! On regaining the lead, declarer could now drop the Q of spades, of course and bring his contract home.
Hey, Mr. West! Nobody can win the J of spades but you. And there's no reason not to take your ace. But when you're second hand, someone else might be able to take the trick. So you go low, allowing for the possibility of a now stiff K or doubleton Q, no? What's your partner supposed to do? Kick you under the table?

I recently saw my K of trump get gobbled up by an unthinking partner. Starting with a K doubleton, I had been granted one ruff, and I believe my partner got one also, which is why we were getting down to a skimply number of trump. In any event, declarer led a low spade to the Q x x in dummy, and as soon as I saw my partner hesitate, I knew my K was a goner. What's there to hesitate about? You go low, allowing for the possibility that your partner can win the trick, and you've still got your ace.
My partner kept saying, "It didn't occur to me that you'd have a bare K." He must've said it 3 or 4 times. I didn't say a word, but I was thinking, well, why not? Isn't that part of a sound game to let your imagination rove over why you should win or should duck?
Yes, there are times when you don't wanna be so stingy about cashing the ace that it's the only trump out, allowing declarer to run winners and get ruffs without having to spend two trump, which would've been necessary had the defender taken his ace, preserving a low trump. And especially when a defender can see that his partner can't win the trick would it probably we wise to go up and preserve that low trump, though to be sure, it often won't make any difference. But when your partner might win the trick, that's novice bridge to go up, smothering his honor. Or pre-novice, maybe.