David Brin, a scientist and award-winning author of science fiction, said, "There's no doubt that scientific training helps many authors to write better science fiction. And yet, several of the very best were English majors who could not parse a differential equation to save their lives."
At the bridge table, we love majors and dislike minors up to the game-level, because in a major we have to win one fewer trick to get the game bonus. However, when climbing up to a slam, minors are fine because we need 12 or 13 tricks whatever the strain.
When you have game values but do not find a major-suit fit, you steer toward three no-trump. Only if you are sure that contract cannot make, do you -- kicking and screaming! -- play in five of a minor.
So, at a low level, we try to find a major-suit fit. Look at the South hand in today's diagram. After opening one diamond and hearing partner respond one heart, South must rebid one spade, not two diamonds. If partner does not raise spades, South can show his long diamond suit on the next round. Here, of course, North raises to two spades (promising four-card support), and South jumps to four spades -- when you smell a game, bid that game.
The defenders start with three rounds of clubs. After ruffing, how should declarer continue?
South must get his diamond suit established, and the heart king is a red herring. Declarer should draw two rounds of trumps, cash the diamond ace-king, ruff a diamond on the board, play a heart to his ace, and lead out winning diamonds. He loses only two clubs and one trump.