Since my early days of learning bridge, I’ve been told how not to allow a ruff-and-discard as a defender. In general, one almost never benefit by leading a suit which allows declarer to ruff at short hand (usually dummy). Leading that suit is probably the worst choice out of 4. If possible, usually it’s best to lead a trump. On BBO, there have been numerous times where I stretched to bid a doubled contract with obvious losers going for down 1, which somehow made because the defender allowed a ruff-and-discard. Most of the time it happened when the defenders won A-K in a suit and then decided to lead a Q into a void in dummy which had 3 trumps. Those who made the mistakes includes players who claim to be intermediate or even advanced. In fact are there situations that I’m not aware of that the defender can actually benefit in a ruff-and-discard? Were those players that made the mistake simply taking calculated risk that failed?