Discards in a suit already played

[baabaa]

Me and my partner play attitude discards against both suit and notrump contracts. However, it’s a bit unclear to me if attitude should still apply if we discard in a suit already played, either by us or the opposition.

 

Sometimes our high cards in the suit will already be known, for example if we lead Q from a sequence against a suit contract. Also, you are usually not interested in a suit that has already been opened by declarer earlier in play. Playing 4th best leads against notrump, it also seems useful in many instances to discard our lowest card from five or more, giving partner count (this does not apply as much against suit contracts since here we play 3rd/5th).

 

What is common agreements here, and what do you recommend?

[Stephen Tu]

Normally, if count has not been indicated or completely clarified, give count (std present count most common). Else (or if bidding/previously play indicate count is clearly irrelevant to both partners), suit preference, but keep in mind a fair amount of the time partner is just trying to make a neutral safe discard.