Some common sequences:
1♥ – 1♠ – 2♣ – 3NT
This is good in some ways. Opener’s minors are unknown, responder could have four spades. Both these might help in the card play.
Of course opener might have five hearts. Responder may wish to check for a 5-3 heart or spade fit. Good if it’s there. If it isn’t, too much of opener’s shape may be revealed.
Countering that, revealing shape might allow responder diagnose a problem with 3NT and head for five of a minor, or four of a major in a 4-3 or 5-2 fit. Two relays establish a game force. After that, the partnership can occasionally switch to natural to check out other strains. Continuing relay may pinpoint the notrump weakness.
| S – AQxx H – xx D – Kxxx C – Kxx | 1D – 1S 2C – 2D 2S – 2NT 3C – ? | S – Kxx H – Ax D – Axx C – QJxxx |
East does not jump to 3NT over 2C because opener might have five spades. 2S showed four diamonds, so 3NT is plausible. (Two balanced hands with no major fit) 2NT seems cost free. It reveals opener’s exact shape but that is unlikely to matter in the play. When opener shows 4-2-4-3, East pauses to consider alternatives. A good tip is “When relay reveals that the opponents have a 9-card fit to lead against 3NT, think of a suit game. On the actual, 3NT has no play. 5C needs a fair bit – such as trumps to break plus 3-3 spades or a squeeze. 4S is quite a good spot. Can they reach it?
Maybe via 3S over 3C to offer the 4-3 fit. You can still reach 3NT when opener has S-Axxx and H-Kx or Qx.
The other time to break into natural is when you want to check out stoppers or are concerned about right-siding.
| S – Axxxx H – Kxx D – Kxx C – xx | 1D – 1S 2C – 2D 2H – 3C 3D – 3S 3N | S – Qx H – xx D – Axx C – AKQxxx |
East isn’t much interested in