The writer, after the analysis of many thousand hands, believes that at "no-trump" the first discard from strength, i.e., the long suit or the suit you wish partner to lead, is the safest and best, both for protecting the hand and for showing the suit beyond possibility of mistake.
The main advantages of the strength discard are:
It takes but one discard positively to show the suit wanted.
You can protect the high cards in your weaker suits without deceiving your partner.
It does not show the dealer so clearly on which side to take a finesse.
By showing your suit earlier in the hand, you enable your partner to discard to better advantage.
There are but few "no-trump" hands in which it is possible to make all the small cards of one's suit against the dealer—unless it be the suit first opened. Occasionally the suit in which the dealer is weak in both hands will be made; but more often this suit is never brought in, because the adversaries do not know the cards they hold in the two hands.
For years whist authorities have agreed that with trump strength declared against you the first discard should be from strength. Why, then, when strength in all of the suits has been declared, should not the strength discard be the best defensive discard for the majority of bridge hands? In order not to lose an opportunity of making all of the long suit, players will continually unguard cards in the weak suits which, if properly protected, would win tricks; and when using the weak suit discard these cards must be unguarded in order to show partner your suit.
There may be an occasional trick lost by discarding from strength at "no-trump," but there are so many tricks thrown away by unguarding honours in weak suits, and so many games and rubbers lost by guessing the wrong suit, that Bridge Players will find the strength discard will save more and lose less than any other discard. You do not expect to win on your adversaries' make; you hope to prevent their winning a large score.
If you have once led, you have shown your strength, and may then discard from any suit you wish.