Fair point Bookworm, maybe I should have used another example, and the one you have proposed is very applicable. I have been known on occasions to fly to an airfield more than 50nm from base, where I do not have to pay landing fees, and spend an afternoon circuit bashing. I then might land, have a coffee, refuel and fly home. The proposed regulations would seem to require me to be carrying reserve fuel whilst flying circuits. I personally feel that individual captaincy decision-making might be a better policy here than imposition of an arbitrary figure.