Source:  By Alan Truscott One basic advantage that the expert has over lesser lights is that he has a deeply rooted awareness of distribution. The common patterns are so ingrained that he rarely has to count up to 13. If he has a 5-3 trump fit, for example, and one player shows out on the second round, he knows automatically that the other defender began with four trumps. He has seen so many thousands of 5-4-3-1 distributions, both as hand patterns and as suits around the table, that the number ”four” clicks into place without effort. The expert thus solves routinely problems that cause others to struggle and perhaps fail. Problem for West to Solve: South Dealer; Both Sides Vulnerable
 J 10 9 8 5 2 A Q 4 A K 9 6 K 7 5 2 A Q 3 10 8 7 2 10 7 A 6 4 3 8 6 6 3 J 8 5 4 2 Q K J 10 9 7 4 K J 9 5 Q 3
 West North East South 1 Pass 2NT Pass 4 All Pass
2NT= FG, no heart fit no singleton or void. An example is the diagramed deal, which should be viewed as a defensive problem for West. Cover the East and South hands and plan the defense in four hearts after a simple uncontested auction: one heart; two no-trump; four hearts. A diamond lead has been won with the ace in dummy, and East has played the three. South could succeed by leading trumps, but he plays the queen, king and ace of clubs, discarding the spade queen. What should West do after ruffing? He has one trick in the bag, and has two sure trump tricks. He also has a good clue to the declarer’s distribution. A doubleton club is known, and there must be at least six trumps to justify the jump to four hearts. A singleton spade seems likely, making the distribution, in all probability, 1-6-4-2. With that possibility in mind, the expert West leads another diamond. If the distribution is what he thinks, he will be able to give his partner a diamond ruff. There is no hurry to play a spade: If South began with more than one spade, he will still go down. The only risk is a very faint one: South might have begun with 2-7-2-2 distribution, in which case he has misplayed the hand by playing clubs before diamonds. The less experienced players would often play a spade in this position, allowing the contract to be made. They would succumb to the urge to lead the suit that the declarer is discarding, and they would blame East in the post-mortem for his play – his correct play – of the diamond three on the first trick.