Here's a comprehensive guide to strength training that I recently found. I like all of the variations of exercises that are illustrated if you don't have access to heavy equipment in a gym.
I'm not sure that only doing 50-70% of the maximum number of reps is going to coax the fast twitch muscles to strengthen and grow to their potential. So if I can do 10 reps with a given resistance, I should stop at 5 or 7? Seems a bit off. And I'd be interested to know how the researchers concluded that 3 sets per exercise is the sweet spot.
I had a similar conclusion when I read it. If you never go to failure, then where does progressive overload fall into the equation. In other words, how can I get stronger if I'm always stopping short of what I'm actually capable of doing?