hmmm british sarcasm???
well what is the purpose of a flight plan....
1 to make sure you know where you are going and how to get there.
2 to make sure you have enough fuel for the trip.
if you have enough fuel on board you can work out the rest as you go if necessary.
dont get me wrong. I know of competent private pilots who take a week to flight plan a long flight but most of that time is spent in relearning half forgotten methods.
he ought to be a lot more certain and a lot faster.