Son is a 10th grader-second year of xc. Last year - Year 1 (first year of running) went about 19:15 on average for 5k on about 35 mpw. This year after a summer of 12 weeks of about 40 miles base and a season under his coach (about 35 miles per week with a speed workout or two mixed in) is now about 18:45 for 5k. He is frustrated that he is not faster. He is the third runner on his varsity (not a very good program and a very small school). He would eagerly build up to 70-80 mile weeks over the next two years and a summer of doubles if he thought it would have a major impact. But if the gain is just 15-30 seconds per 5k then why bother.18:xx is still 18:xx. At what point is a runner working hard enough to determine that he really has limited talent? Any thoughts?