How can the organisers decide whether info relayed from a pilot to their
personal base/retrieve team is not also intended to be of benefit to to
other (team members) pilots?
What is to stop 3 pilots scouting out 1/2 hour before and, because pilot 4
understands the code used by pilots 1-3, p4 knowns which route (1-3) is
favourable?


Pilots who want to cheat don't need to go to such lengths. They just
go off on some other frequency, or carry FM radios. The rule isn't
enforced -- we rely on good sportsmanship, and the disgrace that would
follow if someone were caught. For the moment, that seems to be
working. Reports I have heard of bending this rule are confined to
regionals or low scorers. Few US national contests have been won by
pilots flying together, at least so far, so the question of radio
contact really hasn't come up in any situation that anyone really
cares about it.

John Cochrane