How can this be hard to understand?
Why would you have a high school kid running nearly two hours?
College kids would not need two hour runs.
I would cap anything over 90 minutes, regardless of miles.
You are not training for a marathon.
Think return on investment. What are you getting out of your training, at what cost, at what risk.
You can train a lot with low risk/high return. It is not hard to figure out. First,Toss out your books and formulas.