"No one would try to memorize all the percentages" As someone who studied and memorized 20,000+ words to improve my tournament Scrabble play, this made me laugh. If knowing the numbers is truly advantageous, there's likely to be a subset of competitors willing to work to get that edge. Maybe bridge is different, but the games I've been serious about (Scrabble and poker) both rewarded a significant amount of focused s…
Because in duplicate bridge you are scored not on your absolute result, but on your result relative to people who played the same hands as you, the tinyest edge is magnified.
The basic card-splitting rules are known even to the most rank beginners in duplicate, and there are definitely players who know the percentages as well as any poker player. In a way it's actually easier, as you know where half the cards are as soon as the first lead is made.