Here's a hand that came up at the club (matchpoints):
At my table, I opened 2NT in second seat and partner raised to 3NT. Clearly, with the insight of double-dummy, North should lead out his hearts from top to bottom and achieve a +100 score.
But let's say North figures that establishing his longest and strongest suit (with two side entries) is the proper thing to do and leads a low spade. This is what happened at several tables and most of us took all of the tricks for 720.
But it shouldn't have happened that way. There are only eleven top tricks and, providing that the defenders don't get mixed up, there's actually no squeeze, whether single, double or triple.
North must realize that the most his partner can hold is two or three points. Unless West was Zach Grossack or Harrison Luba, for example, in which case South could easily hold four or five points ;)
Let's say that declarer calls for dummy's king which wins and then crosses to the CA. What can South hold? The club king? Seems unlikely because declarer might have cut himself off from those clubs by taking away dummy's entry. By the way, do you see how important it is (usually) to play the highest card from hidden equals? It causes the opponents to be less than 100% sure where the lower equal (the king in this case) actually is.
So, probably declarer has the king. Then, what useful card could South possibly hold? The heart queen? Or maybe he has only the jack. Either way, North can immediately see that the one suit he must guard is diamonds. He will have to make six discards on the clubs: when the clubs are finished, he will have five cards left: three diamonds and two others. But, unless he keeps a small heart and/or a small spade, he can be end-played into leading away from his queen of diamonds. So, he must choose: keep a high heart or a high spade. Which card is South more likely to hold: ST or HQ? at this point, it's a bit of a toss-up. But North doesn't have to decide just yet.
At this point, proper technique by declarer against expert defenders would be to cash the two top diamonds and hope for a squeeze to materialize. But against defenders who discard more or less randomly, it's probably better to just run the clubs (which is what I did).
So, when declarer plays the CK, North must immediately signal which suit he will guard or, if that's impossible, to start showing which suit(s) he will not guard. Regardless of the carding scheme by defenders, North has an appropriate diamond to discard. The other players follow suit. On the small club at trick four, North will have to play a neutral spade (the five, assuming that he started with the three). South now must decide which suit he will guard. It doesn't matter which he chooses on this hand, as long as he sticks with it. Let's say that he discards an encouraging heart. Now, North can throw that other small spade, thus confirming that he will guard diamonds and spades. The important point is that, although it's possible that the defenders may already have made an error, they must stick with the plan. In this scenario, one error might cost an extra trick. But switching plans will likely cost two tricks.
North will immediately throw the two high hearts and the SQ (implying the J). South will pitch all of his diamonds and two more hearts. Although it takes guts for North to jettison two high hearts, he should remember that when he has most of his side's assets, the little exit cards can be as precious as the high cards.