One of the earliest and most oft spoken bits of advice I have heard is 'Do not move your shoulder'. This has always made sense to me, except just the other day I was watching Phil Taylor throw and his shoulder jumps oh maybe fifteen feet when he throws...

..so how does he get away with it??

:-P

Then there is the 'keep the dart level' lie...

Your right David, and I also noticed another, John Lowe talks about keeping the elbow steady, yet I seen footage and his elbow moves about. I think its near impossible not to have some movement, maybe they should say try to keep as steady as possible?

We are all so different though and our joints do not move in perfectly straight planes so we just have to learn what works best for us.

yeah ya gotta move it some. But avoid dropping ya shoulder IMO

John Lowe in his book does make mention of how pro players have "unique" throws that they have developed and perfected. The advice that he was giving is directed more, in my opinion, at this is what you should try to do to start. Then, as your game and throw develop you tweak it to your own personal preferences.

Like grip said, no two people's joints behave identically. So, it is only natural to see a variety of stances and postures that can all produce the same results. The trick is to learn what yours is.

I do also believe that the more you allow to move, the more you have to correct for. So, by minimizing the number of movements there are in your throwing action the more likely you are to throw consistent darts.