So I generated a bunch of example hands for partner, under the constraints that we have this hand and RHO has 7
♥ with 5-10 hcp. After throwing out the hands where partner has an obvious balancing call, here's what I got:
1.
♠KT8654
♥T
♦T76
♣986
Partner might pull 3NT to 4
♠, in any case a number of four level contracts (spades, clubs) are likely to fail by a trick and 3NT is awful. Passing 3
♥ is the winner.
2.
♠J98743
♥86
♦764
♣T9
Again passing is the winner. Double and pass 3
♠ from partner might survive, anything else awful.
3.
♠K965
♥A97
♦94
♣Q986
Bidding wins here as both 3NT and 5
♣ have good prospects. Probably a 4
♣ overcall is a bit better than 3NT, since if the clubs don't behave you are down only one instead of a zillion.
4.
♠QJ876
♥3
♦Q65
♣QT76
Some play for 5
♣ or 4
♠. 3NT is a disaster. Pass is an okay "middle of the road" option, bidding 4
♣ seems to work out pretty well too.
5.
♠KQJ6
♥Q8
♦QJ97
♣Q98
Conceivable partner might balance on this, but I think not obvious to do so. Probably 4
♠ on the 4-2 fit is the best game! Perhaps a win for double and pass 4
♠ from partner?
6.
♠8654
♥Q63
♦T876
♣T7
Any non-pass action here is probably awful.
7.
♠KQ7653
♥43
♦J64
♣K6
Double and 4
♣ both win here as a good 4
♠ should be reached. Bidding 3NT is okay if partner pulls to 4
♠ not not clear he will. Pass misses a pretty good game.
8.
♠KJT63
♥K8
♦9764
♣K7
Both 4
♠ and 3NT from partner's side are okay, but not spectacular. Kind of a toss-up.
9.
♠JT86
♥A
♦T6
♣QJT987
Here 5
♣ is cold and even 6
♣ has some play. 3NT is basically on a club guess, not bad but I'd rather be in 5
♣. Pass is a big loser here.
10.
♠QT93
♥T8
♦Q64
♣KJ98
Bidding 3NT seems disastrous. A 4
♣ overcall is fine if partner lets you play there. Pass probably beats 3
♥ a trick.
11.
♠Q987
♥A76
♦JT84
♣K8
Both 3NT and 5
♦ seem okay, but not spectacularly good. Not clear what is best on this one either.
12.
♠Q9753
♥K
♦J965
♣KJ7
Not much chance for 3NT (unless maybe from partner's side). Five of a minor has chances but is not very good. Pass is best here.
13.
♠JT65
♥AQ3
♦86
♣KT97
Good hand for 3NT. But notice that 5
♣ also has some play. Pass misses a pretty good game.
14.
♠T953
♥-
♦JT98
♣QJT97
Five of a minor is pretty good. 3NT horrendous. Pass misses a pretty good game (although I suppose LHO is likely to bid 4
♥ and give you another chance).
15.
♠J865
♥Q
♦QT86
♣QJ86
Some play for 5m but it's less than 50%. 3NT is awful. Pass is the winner.
16.
♠QJ6
♥T54
♦QT4
♣Q876
Some chance the suit blocks in 3NT. 4
♣ is okay but not five.
17.
♠QT83
♥KQ7
♦T9654
♣T
Partner has two heart honors! 3NT is best here, but it still might fail. 5
♦ is probably down on a heart lead and ruff (lose two diamonds and a spade). Pass is okay.
18.
♠9743
♥K8
♦854
♣KQ76
Again, 3NT from partner's hand has chances. 3NT from our side not so much. It seems likely that 4
♣ is down one, but 3
♥ could make!
19.
♠QJ9873
♥K6
♦J
♣K876
4
♠ from partner's side is quite good. Pass misses the game. 3NT may play the wrong game (and from wrong side) unless partner pulls to 4
♠.
20.
♠JT865
♥T
♦QT8764
♣K
5
♦ seems like the spot. Double or 4
♣ gives us a shot to reach it; 3NT probably will get passed out and set. Pass misses another good game.
21.
♠KJ86
♥9
♦QT986
♣J87
Some play for four of either minor, not so much for five. Bidding 4
♣ probably lets you play there, pass and 3
♥ might make or be down one.
Looking at these, it seems like bidding 3NT is usually awful when opener has the "normal" seven card heart suit. It has a few wins but a lot more losses (some very expensive). It's a bit less bad if partner will normally pull to 4
♠ on a six-card suit there, but this seems non-obvious since 3NT could be based on a running minor. On the other hand, overcalling 4
♣ seems to win over pass quite frequently, although there are occasional
huge disasters when partner is broke.
Adam W. Meyerson
a.k.a. Appeal Without Merit