We find that when both hands are balanced, with no five-card suits, six notrump and six of a major don’t become good contracts (likely to make more often than not) unless there are at least 33 combined HCP. For details, see Real World Bridge 7: The Slam Zone. For now, we will simply say that many players drive to slam when both hands are balanced and the combined HCP are likely to be 31 or 32, and those slams typically do not make.
However, when there are long suits, very good slam contracts can be reached with many fewer than 33 combined HCP. In these situations, we find that HCP are much less important. Instead, these sorts of factors become critical: how many trumps each of you hold, your shape, and whether your Kings and Queens and Jacks are in partner’s long suits rather than in partner’s short suits. For example, here is a very good six spade slam with only 27 combined HCP:
