[FrancesHinden]

In a match on Sunday my partner had

10xxx
KQxx
AKxx
K

at game all
The auction started on his right:

1S P 2S P
P x* P 2NT**
3C P 3D 3H
3S 4H*** all pass

*four small spades...
**usually two places to play, might be extra values with hearts
*** partner must have five hearts to volunteer 3H here, so either has extras or has a second five card suit which must be clubs.

partner had
K
Axxxx
xx
109xxx

not a great spot, but just about worthwhile vul at imps, +620

[awm]

This has to depend a bit on style. We have to decide whose responsibility it is to take the aggressive balancing actions. The likely alternatives are: (1) The person in balancing chair (2) The person with shortness. The advantage of the former is that both opponents have limited themselves, making it less likely they have game values and double you off for a number. There are two disadvantages: one is that the worst time to get doubled off for a number at the three level is when opponents don't have game values (since now -300 is disastrous instead of a good save, and -500 is a huge loss instead of a small one). The other is that it's hard to work out their degree of fit -- you usually don't want to let opponents play a nine-card fit at the two-level but an eight-card fit (especially in spades) is okay (LOTT says you will usually trade +50 for +110 or -110 for -50 if you're lucky, and might go -300 if your side has no 8-card fit).

Anyways, if you play the first style you expect that partner would never double with a 24(34) ten count (say) in a live auction like Pass-1♠-Pass-2♠ and that partner might well pass with a singleton spade too (especially if not a max passed hand). In this case you have to balance. Occasionally you will go for a number, but there are many "good hands" for partner where you get a plus score. If you play the second style, you expect that partner would have doubled 2♠ with a 24(34) ten-count or with a 1444 eight-count (for example). Obviously such a double would be dangerous -- you might've gone for a number if opener had a lot of extras. But since partner didn't double, you know partner doesn't have one of those nice hands. Now balancing is a bad idea -- the "best hands" for partner to hold have been eliminated, partner will almost never have a singleton spade and probably has a pretty lousy hand (since 10-11 points and doubleton spade also would act).