Poliquin's 1,6 principle is basically this:
You do a heavy single and then drop the weight and do 6 reps. The 6 reps are easier then they would otherwise be since your fiber recruitment is better because you just hit the muscle with the heavier weight.
It's not really that useful for bodybuilding purposes, since you would be conditioning your body to the heavier weight, and this would be the primary hypertrophic stimulus for the muscles involved, the 6 reps would function like a drop set. But it is useful of course for maxing out, or if you're trying to rep a particular weight a maximal amount of times.