This is a much more challenging hand if you don’t play 2/1 Game Force. Without 2/1 Game Forcing, after the bidding starts 1♥ – 2♣ – 2♦, South has a difficult bid. What’s forcing? What’s not? South’s only recourse is to bid 2♠ (a new suit) to make a forcing bid. North bids 3♦ (to bid out his shape of 5/5) and now South’s 4♦ bid becomes murky. North is wondering, “Did he bid 4♦ because we don’t have a spade-stopper for NT? Does he have a hand that’s thinking about slam or trying to stop? Should I bid 5♦ or cuebid? If I cuebid 4♥ will he think I want to play 4♥?”
With 2/1 Game Forcing, it all becomes easy and clear at South’s second bid, 3♦ showed a hand with game forcing values and at least four clubs―usually five. 3♦ is natural, setting diamonds as trumps. We are already in a game forcing auction. Trumps are diamonds. Any bids below game are cuebids attempting to discover if slam is feasible.
Patty’s books are listed on Amazon.com. You can learn more about this technique by reading Patty’s book, Your Bridge to Conventions; 2/1 Game Force System.