Since this seems to be newly-resurrected, I have to say, I've been using this warmup for many months now, through a few different routines and it is great. At the top of the thread, i was a bit skeptical (my username was BradG then), but back then, I think I was trying more to be a pain in the ass than have an open mind.
I tweak it a little bit, but mostly I do:
50% x 10
67% x 6
80% x 3
90% x 1
Work sets...
The key to remember is that you only have to warm up a body part
once, and that includes the secondary muscles. That is, if you just did a back workout, you don't need to warm up the biceps. I usually just do a 75% x 8 just to get used to the movement.
Sometimes I have been tempted to skip a few of the w/u sets 'cause it's not the most stimulating thing in the world to warm up. And the times I did, I feel I got less out of the working sets. I am soooo glad I decided to give this a try and stick w/ it.....