Notice Your Trump

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

Declarer made her contract, but got a mediocre score for just making when an overtrick was possible. And this was after getting her heart finesse right. Opening lead taken by the K. Declarer then went to the K of diamonds and pushed the 8 of hearts through to the K. Now came another club and declarer, leery of cashing a third round of clubs, now continued the hearts, the J was covered, the trick then taken by West, who led a spade.
Declarer went up with the ace, ruffed a spade, cashed the third round of trump, and now cashed two more rounds of diamonds and conceded a diamond to East, then picking up the last two tricks with a trump and the 5th diamond. And after such a promising start. Here is what the hand looked like at trick 6 on the spade lead after West has won the second round of trump:

A Q 10 5 2
7
------
J 10
K 8 6 4 J 9 7
4 ------
9 7 J 8 5
9 7 6
3
10 9 6
A Q 10 6
------

With all high trump, declarer now has an easy path to her contract, to wit: win the spade lead with the ace, ruff a spade, which she did, ruff a diamond, back on a ruff of anything (with the highest two trump and only one more remaining out), draw the last trump and run your diamonds.
Declarer actually had another means toward her contract on that spade lead, to wit: take the finesse, cash the A of spades, sluffing a diamond, take one round of clubs, sluffing a diamond, and now declarer is home free, holding the top three trump with only one out. I don't like this quite as well as the first line of making use of dummy's 7 of trump for a diamond ruff, but is it any riskier than banking on the J of diamonds falling on the third round? Whether declarer did this consciously or not, I cannot say. But please note that the J of diamonds falling doubleton wouldn't help declarer, for then the long-diamond holding with be 5 cards headed by the 9, and declarer would still lose a diamond. So it has to be a twice-guarded jack for this line of play, and that's just too specific a holding to bank on.
Yikes! What am I saying. I just noticed a 100% safe line for an overtrick at that point. Good heavens! Cash the 8 of hearts! Oh! Oh! Oh! No, I can't believe it. Declarer pushed the 8 of hearts through on the first round of trump as mentioned above, okay. That shoulda been "Cash the 7 of hearts". But declarer had played the seven on the second round of trump! Leading to the Q 10 9? The seven was necessary to lead? Isn't it strange how that careless profligacy queered a 100% chance for the remainder of the tricks. A seven! Anyway, had the 7 or 8 still been in dummy, declarer could simply have drawn the last trump and cashed two clubs, sluffing two diamonds for a far better score.