I came across this gentleman's site awhile back and was blown away by some of his claims. Starting with this one:
http://fellrnr.com/wiki/Tempo_Runs
Where he claims Tempo Runs are ineffective.
He makes a few other fun claims too, on different threads. Among them are...
- Running 3 or 4 days per week is optimal, even for elites (in his marathon training program comparison where he decides RUN SMART is one of the best choices because of this)
- HIIT is king
Anyway, I thought I'd throw this out there for you piranhas