Here is a hand I recently observed on BBO. It’s illustrative of good slam bidding, using cue bids to get to the best contract.
Here is the hand:
The bidding started as shown above. South can discern the excellent slam potential of the hand. North had opened one diamond and guaranteed four hearts by raising to two hearts at second turn. Moreover, South knows there is a diamond fit, including prospect of parking that losing club on partner’s fourth diamond.
Most Souths blasted into Roman Key Card Blackwood at 2nd turn. That’s not the recommended strategy with two potential spade losers. Better is to cue bid your way there.
Recommended approach:
At 2nd turn South should cue bid 3 clubs, showing first round control and interest in slam. South is hoping partner will now show first round control of spades. When partner does exactly that, South should cue bid 3 Diamonds (first round control). Now partner may bid 3 spades, showing second round control. If so, you will be in grand slam territory.