the reason behind only doing 4 weeks of anaerobic workouts is, I read an article that Arthur lydiard wrote… http://www.geocities.com/gprrc/lydiard.html
he said anything over 4-5 weeks of real anaerobic training will actually decrease your aerobic fitness.
the sharpening phase anaerobic sharpeners are very short in comparison to real anaerobic work, and this only keeps your edge on your anaerobic systems but doesn’t dull your aerobic fitness.
All I have learned on this topic are from Hadd, John Kellog, and Arthur Lydiard. Let me know if i misinterpreted something