I'm not a expert on Fridrich, or Roux even for that matter, but this is my take on it. My first block is always Blue on L and White on D. Always. This helps me with recognition and look ahead. Colour neutrality probably would give me fewer moves though, but personally, the time I save in number of moves I lose in recognition and look ahead. I will probably go double colour neutral, and then quintuple because it is always nice to have an easy block, but I will always look for the Blue-White block first, always.