U turns can be used or not .. the idea I believe is to cut out a threat, a team you don't like, a team that has screwed you over or an attempt to advance your position in the game .. once you are past the U Turn point, you are safe .. if it could be retroactive, the Chips would have been in trouble .. what point would they have if only used on non-elimination legs other than maybe slowing a team down on the start of the next leg .. ??
It seems to me that in many cases, the U-Turn is not used ..
The U-Turn is the exact opposite of the Fast Forward ..