I was just compiling some personal stats and found that I've only beaten a handful of boards more than 5 times even though I've played almost all of them.
I've only played about 500 games though.
classic (38 times out of 92)
world 2.1 (6/38)
USA (8/20)
British Isles (6/18)
Cairns (6/16)
Portugal (6/13)