Defence to the opponents’ 1NT opening is an area fraught with hazards: some in the bidding and some in the theory of it. This hand is a typical example where East opens a strong 1NT. You might not like the five card major but that’s a common expert treatment when it’s in the 1NT range. You may not like the king-jack doubleton diamond but this is what happened at the table with a well known Sydney pro sitting East. Now there are a number of players who see the South hand as beating 1NT but they can’t double because that shows a single suiter. Their first action is to pass, as here, but when the opponents run, they have a problem. When South emerged from the bushes with 3H, North thought this was a protective action based on an assumption of values in his hand since West had not invited game. There is also the matter of the common belief that if they open a strong 1NT, our side cannot have game values.
It was a poor outcome when the opponents played the safe 3NT in the other room. 4H also makes, except on a diamond lead because you lose? The entries to play spades twice. These hands are so much easier to handle if you can bid 2H or 2S to show that long major rather than hiding single suiters variously in your double, 2C or 2D bids. The defence is pressed for space and, if the auction is competitive, either-or bids just cause self-inflicted problems. If you are comfortable with this then you can use 2C and 2D to show hearts and another and spades and another respectively. These hands can be 5-4 or 4-5. This method belongs to the ASPTRO family and Mr. Google will tell you all about it. The advantage is much larger relative to DONT when playing pairs since you tend to play in the major rather than the minor. Consider holding a 4243 hand when partner bids a DONT 2C. You have to play 2C because it might be your best spot and cannot look for the major fit in case partner has hearts and clubs!