Jacoby style raises, part 1.
For many years now, using 2NT as a strong raise of a major has been the mainstream solution for how to show partner you have a good hand and the values for game. The "standard" treatment is usually any game forcing hand with 4+ cards in opener's major. The basic responses are shortness on the 3 level, secondary suits (5 cards) on the 4 level with 4M being the lightest balanced hand, 3M being the strongest, and 3NT somewhere in between.
From a theoretical perspective, there are a lot of problems with this structure. The first glaring problem is a simple one: opener, the hand which is about to be declarer, does a lot of describing of their values and distribution. This is true even if there is no real slam interest for the partnership; opener describes immediately, responder jumps to game (maybe), but the damage is done. It's even worse if cuebids are taken by both sides, making it easy for the defense.
A lot of partnerships deal with this issue by using an artificial response structure to 2NT, usually including a 3C minimum step. This at least lets us get to game when neither hand has game interest without describing to a fine degree what they have. While this is a large improvement over basic Jacoby, there are still some areas I feel could be improved.
One of the flaws with the Jacoby model is that of Captaincy. If we use Jacoby on all hands where we have a game forcing hand, our effective range as responder is something like 12 to 25. This can be very awkward if we are on the low end of a game force while the opener has extra values; trapped into responding to the Jacoby relays, opener never has a good opportunity to describe all of his hand. If responder has a minimum, he has to express that quickly to avoid the description trap I described above. Valuable bidding space can be lost when we are near the slam zone without high level safety.
Early in my partnership with Joel Wooldridge, we dealt with this issue in an unusual way: our "Jacoby" bid had a much higher minimum. We would only bid Jacoby with hands that had slam interest, about 16 HCP and up. (Hands with excellent slam prospects could be less).
By "pre-showing" the extra values, we never needed to worry that the "wrong" hand was in charge since if the other hand was stronger we were surely slam bound. (In fact, we reversed the "improvement" listed above. Our first step showed extra values, not minimal. With the minimum hands we could afford to start describing immediately since we knew that one member of the partnership had already expressed interest in more than game. At that point it became worth the price of describing declarer's hand.
These methods suited us well for many years, but at this point they have been retired. In part 2 I'll describe what I've used in other partnerships and what I am using today.