The situation you want to avoid is one where the wind is high on Friday or Sunday and a team decides to not go out so they can average their other scores. The two to three day conversion is intended to permit a reasonable scoring opportunity for those who can't make all three days of racing fit their schedule without penalizing anyone. If you show up on Friday and are able to sail but choose not to (for whatever reason) then you don't fall into this "special needs" category...i.e., no soup for you.