15 hours is a good amount to do a lot. A different coach might tell you differently what to do based on a lot of things like...
What kinda races do you plan to be competitive in - age, class, location...?
How old are you (maybe answered above)?
How much sleep do you get?
What is your diet?
Do you have weights/gym available?
If you are male < 25 you can do high intensity more than if you are older. The program might be lift more and sleep more. One approach is to bulk up in the off-season.
Focus on speed and power over base.
If you are dong long 90 mile plus races (I expect you would not be doing those and asking here) doing more base miles would be more important.