Bridge Chestnut 8 - "Always maintain length parity with dummy"
This chestnut is a useful guide but not commonly identified at the club level. It applies when declarer is running a long suit and you have to discard after dummy. You will probably be aware of how many discards that you need to find. Partner will be giving you count and you will have some information from the bidding.
As declarer runs a long club suit, he begins to discard hearts from dummy. You have a nasty surprise for him in spades. So, you commence to pitch hearts as well. If it transpires that declarer can make his contract because of your dropped hearts, then he was going to make it anyway. You were squeezed in the majors. It is more likely that he will lead a spade to the ten and your jack. Make sure that you have retained an exit card – a heart. Of course, he may still prevail by removing all cards except spades.
Go to Chestnut 9 - Always play the card which you are known to hold