Consider this deal where South is in three notrump and you, West, lead the jack of spades, won by dummy’s king. Declarer returns the eight of diamonds, losing to your partner’s king. East, a firm believer in always returning the suit his partner led, leads the eight of spades to dummy’s ace.
This does not prove to be an enormous success. Declarer leads another diamond from dummy, forcing out your ace, and eventually winds up making three notrump.
It is true that East’s spade return at trick three would have worked out great if you had started with six spades to the J-10-9 instead of only five. But the fact remains that East’s spade return was a dreadful play.
East should have realized that shifting to the five of hearts at trick three was certain to defeat the contract. South clearly had no hope of making three notrump without establishing dummy’s diamonds, and you were known to hold the ace. As soon as declarer led another diamond, you would take your ace and return a heart through the K-J to quickly settle South’s hash.
The deal demonstrates once again that blindly following a general rule is not always the right thing to do. While the general principles of defensive play are highly reliable in most instances, that certainly doesn’t mean one must follow a rule regardless of the situation. Every play must stand on its own merits.
Of course, it goes against the grain to deliberately play away from the A-Q-9-5 into dummy’s K-J-10, but if the circumstances demand it – as in this case – you must swallow hard and do it. It’s basically a matter of self-preservation.