Try ACBL Speedball Pairs with Steve Raine
Watch Steve play one of the most popular ACBL pair games, Speedball Pairs. How w...
Join Rob Barrington and Anam Tebha as they show you a hand that could have used conventional help. Puppet Stayman is a useful tool that helps our side discover Major Suit fits after we open No-Trump. Check out how it works in this video.
what is wrong (bad) with responder's bid of 4 diam over opener's reibid of 3 diam when responder holds 4 cards in each major?
They went through that a bit quickly. In "standard" or old-style Puppet (at least over 2N-3C), the answers were:
3D = no 5-card major but at least a 4-card major
3M = 5-card major
3N = no 5- or 4-card majors.
If we play this way, then theoretically responder could bid 4D to show 4-4 in the majors conventionall. However, even in that case, it's a waste of a bid; 4D would often be necessary as a slam try in diamonds.
IF you want to play 3D as showing a 4-card major, then you can still bid with both majors as responder by showing one major and if partner denies it, showing the other one. It's a bit awkward, but it frees up 4D to be a natural slam try.
However, I also agree with Anam&Rob that it's better to have 3D as "no 5-card, may or may not have a 4-card major" because that way defenders will be a bit more in the dark. Dummy will show their hand more, but that is only a factor for the opening lead.