Players are used to playing some 5-3 major fit hands in 3NT, though that can come unstuck. Relay is good with those, through being able to check for 6-card fits…
Another hand from the book. South was known to have two diamond honours.6♦ is maybe better but careful play vindicated partner's choice.After two rounds of hearts, ♣K, ♦K, ♣Q revealed…