The 5-Level

The 5-level belongs to the opponent, they say. Overbidding at this level means chaos. Often, minute changes in the distribution decide between top and flop. 

In teams, the outcome of one board at the 5-level can decide the match. The worst switch is that both sides can make their contract. If in doubt, it is therefore better to defend on the 5-level. If both sides cannot make the contract, the difference can be substantial, but not disastrous. If your opponents can make their contract, you need a lot of fullers to be worse. And if both sides can make, you have decided the match.

In pairs, these contracts are usually simply top or zero at a 50% probability. You can decide by your defense tricks. If you do not have many and are in doubt that you can make your contract, pass.

This is from a pairs event. It is quite natural to block with 5♦ here. In fact, 3NT is the better contract with 10 top tricks for +630 instead of +600, making even if West does not have ♣A. But I have no idea how to produce a chance to find it. 

The LAW and reason clearly says that 5♥ should not be bid. Points are even between the sides. But there are only 9 sure trumps in hearts which forbids this defense. The 5-level is for the opponent. In fact, however, it is a good defense if you can manage to go down only twice. South has not much of safe defense tricks. So, it might be an idea to defend.

If you want to play this hand, open the BBO hand viewer here. 

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