“The only logical reason I can think of, is that the take off charts and factors (e.g. CAA) suggest those extra 20m and you decide to play it by the book as it is a training flight.
Maybe the OP will inform us.”
He has already told us that his machine had better performance than a Pitts. With a long hard runway no way did he need the extra 20m to comply with the regs. He probably had more than 5 times what he needed.
Rod1