Strong club systems have many advantages, particularly in slam auctions where information can be exchanged at a low level.
There are also disadvantages, in that opponents have carte blanche to interfere with the smooth exchange of information. On this deal from the Swiss teams in Ostend, East-West were playing Blue Club, where the response to 1C shows how many controls responder holds (an ace is two controls, a king one). South made a simple overcall, because the vulnerability was wrong for aggressive pre-emption, but over the control-showing response North was less cautious. West had shown four controls, so the auction was forcing to game, and East passed to get more info about partner’s distribution. When West made a takeout double he decided that a vulnerable penalty was the best score on offer. He was wrong. West led a trump to the ace and East continued trump. Declarer knocked out the ace of clubs, and crossruffed his way to nine tricks for +730. There is a defence to 3H: West must lead a club so he can give partner a ruff. But it is never a good idea to double a partscore when you require a specific lead to beat it and you have no idea what that might be; and +200 is poor consolation even for a non-vulnerable game. It was galling to be told by Deep Finesse that slam can be made in spades or diamonds