I've never because my father was always changed the clocks over the night before the change. It was rather obsessive; to the point he changed even watches that are saved for special occasions and almost never worn. Scary. Consequently I've never been caught out while I've lived with him, but for the past year when he's moved out I've managed to keep on top of it so far. I think last time I saw my computer clock skip an hour and thought "oh yeah, of course" and changed my watch and clocks over xD