Not every truism is always true, especially in bridge.

Let’s examine this one: “Always cover an honor with an honor.”

You’re sitting North and opposing East’s 3NT contract:

                    NORTH
                    ♠️ K 6 

WEST                                EAST
♠️ Q J 9 8                       ♠️ A 7 3 2

                    SOUTH
                    ♠️ 10 5 4   
 
Declarer leads the ♠️Q from the board. What should North play?

Let’s say North plays the ♠️K. Declarer wins the ♠️A, finesses the ♠️9 and wins a third trick with the ♠️J. No tricks for the defense.

Now let’s say North allows the ♠️Q to win, then covers the ♠️J with the ♠️K. Eventually the ♠️10 will take a trick.

Lesson: wait until the last of touching honors before covering.

Second truism: “Always lead fourth best from your longest and strongest suit against a NoTrump contract.”

Your hand:

♠️ 4 3
♥️ 10 9 7 6 
♦️ Q 5 4
♣️ 6 5 3 2

It’s tempting to lead the ♥️6. Trouble is, you may be losing to the ♥️8. Better to lead the ♥️10, which is the top of a sequence (10, 9, 7 counts as one). 

Third truism: don’t bid 1NT with two doubletons.

What would you do with this holding?

♠️ K 4
♥️ A J 8 5
♦️ A K 10 6 5 
♣️ 4 3

If you bid 1♦️ and partner responds 1♠️, you’re up the creek. You aren’t strong enough to reverse into 2♥️, and you’re too strong to rebid 1NT. It would have been much easier to open 1NT.

The following is not exactly a truism but has become popular usage: “With the opening lead, play the ace of a suit followed by its king.”

That’s fine as far as it goes, but how do you show a doubleton?

Play the king, then the ace.