Where does the 33 HCP guideline for 6NT come from? I realise that there are lots of other factors such as shape, teams vs pairs, vulnerable vs not vulnerable, the quality of the field etc. Presumably there has been some computer modelling over millions of hands to support the basic guideline. I think I read somewhere that two flat hands with 33 HCP makes just over 50% of the time on best play. Many thanks in anticipation.