The law in virginia states that slower drivers must yeild to faster approaching cars.
While this tactic is more confrontational, I must admit that it is certainly safer than riding their ass.
In the past I have avoided doing this because when they don't move out of the way, to me it is more blatant, and I suffer a greater blow to my ego. This causes a more heated situation, which I'd like to avoid.
I've seen multiple people doing it lately though, which to me is good as it means people will consider it less out of the ordinary. The object is to get the person to move out of the way, not create a road rage war where they slow way down, taking insult at your desire to drive faster than they can/want to, and make you a target of their hatred. Whatever manner avoids this yet allows drivers to drive at the speed they desire is the best.
I've seen it take as many as 4 or 5 attempts, but sure enough .. people move. I am looking forward to getting more comfortable with this procedure.