mgoetze, on 2015-September-03, 10:20, said:
Having recently had the auction 2NT-4NT-6♦-6NT, where partner failed to see that playing in my SIX card diamond suit would be best, I'm not so sure it is silly.
What are you gaining? You could have bid 6
♦ anyway with a 6 card suit and bid 5
♦ followed by 6
♦ with a 5 card suit. The sequence 1NT - 4NT; 5
♦ - 5NT thus becomes a waiting bid, usually with 3 diamonds, to see if Responder has anything else to say. This allows you to have your co-operative auctions searching for 4-4 fits at the 5 level rather than 6 level without giving up anything else. It is also closer to the more general rules for a quantitative 4NT bid and entails having to work out fewer special cases. This is why it seems silly to me - adding more complexity with no apparent gains whatsoever. And you will know I do not mind a complicated sequence or two...