Kurious Kyle wrote:
What is this? A running related question that no one can answer??
You might want to give it more than 19 minutes at 7:30 in the morning.
Some people like to ask "If 100% identical runners do identical training except one does X and one does Y, how will their times differ in race Z?" These questions are impossible to answer, because the situation is so synthetic. Look at it this way. Many (if not all) top coaches incorporate a weekly long run into the schedules of distance runners because on average, it helps their racing. Obviously, some benefit more from a long run and some less. In extreme cases, some runners might see no benefit at all from a long run.
So, your answer is anywhere between a little and a lot.