A slightly artificial and labarotary like scenario I know but it helps frame a question that I am interested in.
If I am training for a 10K run in circa 2 months and run 21 miles per week: which approach is likely to give me a better time
1) 7 runs per week of 3 miles each at 7 minute mile pace or;
2) 3 runs per week of 7 miles at 8 minute mile pace.
I know the answer is that a good mix of runs is best but.. if anyone cares to submit a view on which extreme is most beneficial I should be most interested.