Right, Smoove. OP, you need to assume that the opportunity cost for the hard workout day was just another easy 4-6 mile run rather than working on building base mileage. Not everyone can run more mileage. Or maybe they are in fact building (even to 30 mpw) and then sharpening before continuing to build. It's nice to break up all that slow easy mileage. Probably healthy too We all know runners that ran fast times on low mileage. They probably did 'too much' speed work.
Smoove wrote:
You're not thinking this through. Not everyone has the capacity to run lots of miles without injury. Also, many people have limited time to run so they can't get in tons of volume.
Look at it this way: if you could only run 30 miles per week, how would you allocate those miles?
I ran 15:12 my first year of running off of 40 miles per week or so with tempo runs and track sessions.