Agree with you both. If I am keeping an eye on the trend with FG then I update every half hour but will usually have the fuel to go somewhere else anyway. If however the TTF has gone to INTER or TEMPO BN 0500 when I know that I can still get in off a CAT 1 ILS then I will impose the Rumsfeld defense: "there are unknowns and known unknowns" If you have a TTF that covers you for your ETA then I don't consider that you are then required to update the weather in case the BOM wants to hedge its bets.