When I ran in the World Student Champs it was very wet and the terrain was covered in huge boulders. I realised by no 2 that all I had to do was look for the umbrella to find the control Poor Jean Ramsden with a late start got into a reentrant, looked down, saw no umbrella, so went up - she hadn't noticed it had stopped raining
When I manned a control at a very wet WOC Classic we weren't allowed an umbrella Possibly because we were tucked in by a boulder less than 2m from the flag.