I am far from being a careful declarer, but I was quite proud of myself on this hand from the game yesterday:
I ducked the first heart and won the second in hand. I have two hearts, a spade and a club. If the club finesse works, I am up to 7 tricks. A diamond would be the 8th and maybe I'll get one more spade. This is going to be touch and go! Try it the other way. Suppose the club finesse loses. I'll get a heart back, and I'm good as long as South has the Ace of diamonds. Or am I? If South has the Ace of diamonds, I still don't have 9 tricks -- I have two hearts, a diamond, 3 clubs and a spade = 7 tricks before North gets in with the King of spades and cashes 5 tricks. Ugh. Well, in any case, I need to get to dummy to take a finesse.
I play a low diamond to the board and the King wins. Now what?
Take a club finesse with the Jack first. If it loses, the 10 of clubs is an entry. North won her king and played back a heart. Now what?
Count my tricks again. I have 2 hearts, 3 clubs, 1 diamond. If the spade finesse wins, I have 3 more tricks. That is nine tricks in all. But I need to take two spade finesses. This is not the time to play clubs -- I need the club entry to take the second spade finesse. So, I played a spade to the Jack. It held. I cashed the AQ of clubs, led a club to the 10, finessed a spade once more and cashed the Ace. Making 9 tricks. Whew!
This has got to be a good board, right? I had carefully timed it, used every entry and taken the finesses in the right order. Nope. The board was barely above average. We got 6.5 out of 12 matchpoints for making 3NT.
If North goes up with the Ace of diamonds when I led towards the KQ of diamonds, then, because diamonds break 3-3, I will make 10 tricks in No-Trump. But North ducked. If I take the spade finesse instead of the club finesse, I have no more entries to board. I suppose I can lead a diamond again, but it is risky because South is a fine card player too. Holding AJ10, he will duck the first diamond. And once North ducked that diamond, 3NT was all that I could make.
So, my good declarer play was canceled out by even better defensive play by the opponents. And that is how it goes.