Superhumanradio (available via web or iTunes podcast) episode 306 had a interesting discussion on rest interval on growth hormone promotion. His guest was Bob Buresh (dept of health, Kennesaw state).
Longer rest intervals (1-2 minute between sets) promote strength
Shorter rest intervals (<1 minute) promote hypertrophy and asthetics
But he also discussed via testing of two groups, that after 5 weeks, their hormone levels were identical. Meaning that you have to change things up after a while to avoid plateaus.
I'll have to try one or the other as currently, I don't really follow either per se. But I definitely agree with the 4-6 week change in protocol, one way or the other.