Point of discussion - cuebidding

Cooperative slam bidding isn't easy. Look at this hand from the final Swiss match in Montegrotto. You have:

9xx
-
AQT9
AKQJT7

Partner opens 1D, showing 11-13 bal/5M332 or 11-15 with 4-card major and unbalanced hand. Your RHO overcalls 1H (red vs white) and you jump to 3C, a gameforce with 6+suit. Partner bids 3NT and you have your first decision to make; pass or invite slam. If moving on, what's the best way/bid?

Bidding 4H should show a void and gets that vital fact across, but you'd really like to fetch a diamond cuebid from partner and leave more room for exploration and the possibility to sign-off in 4NT (4H also sets clubs and 4NT is no longer natural). Let's say you bid 4C and partner raises to 5C. Would you bid on?

That was correct this time as dummy tabled Kx/KJxx/KJx/98xx and the A of spades where onside (no swing in the match).

First question is, must partner cuebid? When should he signoff in 4NT? When in 5C? This is both a matter of finding the optimal way of handling a situations like this and personal ability and style.

When you had a choice to cooperate previously and didn't (i.e. bid 3NT in example) and partner moves again, my view is that you have to cuebid on any excuse. Repeat: ANY EXCUSE. Being ace-less isn't one of them. Having wasted values may be a reason, but since you bid 3NT partner expects wasted values. You have to focus on remaining useful cards/shape, not thinking 'I have only 6 working hcp when my opening bid promised 11/12+'. And, you have to make sure partner is on the same page. This means that there are hands that can just raise, and there are hands that can signoff in 4NT.

With KQJ/KQx/Jxxx/xxx, I'd bid 5C.
With QJx/AQxx/Kxxx/xx, I'd bid 4D.
With QJxx/KQJx/Kxxx/x, I'd bid 4NT.

Obviously, it's impossible to get to the right contract every time; we have to work the percentages and try to avoid bad slams and get to the good ones. My point is that certain situations calls for, almost demands, cuebids even with devalued hands with wasted values. Especially when a minor suit is the designated trump suit, as there is less room available below slam 'commitment' (when major is trumps, after 4M, you can go with 5-level cue's).

Back to the deal in question, I think that cue-bidding was called for over 4C, and I think the strong hand may have raised to slam anyway since partner didn't bid 4NT, whereby indirectly suggesting useful values.

Work on your cue-bidding 'philosophy'.