Theres an article in Flying a few years ago about a guy in the states, who after working a full day flying had to go from Chicago t NYC to pick up a C180 taildragger and ferrit over night to Wisconsin. hw was just over the shore of lake michigan, which is some 100 nm wide, nice and trimmed could see the lights of Milwauke on the horizon when he drifted off to sleep. When he woke, there were lights everywhere, he had overflown his destination by some 200 nm.......................................all with no autopilot.