This kid is in HS and running 40 miles a week. Yes, 25% in a long run makes total sense. Keep doing it. When you get to 80 miles a week, 25% in a long run probably doe not make sense but in HS, you'll probably never get to that total.
Keep doing your 10 miler weekly.
Wrong. Completly wrong. A person running 40 miles a week would benfit from spreading the mileage throughout the week rather than lumping it all into one day.
Keep in mind a high schooler at 40mpw is probably taking 1 day off, has a workout day with like 5 total miles, a prerace day with 3-4, and a race day with 5. that leaves 26 miles in 3 days, or 10 8 8.