which method involves the least amount of turns

[Ton]

I have a colleague, I gave him a Rubik's cube , he has a new method requiring no turns

He left the cube in its packing and does not scramble it. I guess this is the most efficient method. btw works for any puzzle

 

[qqwref]

That is as silly as the "LL skip" method, it only works for a small handful of positions, otherwise you can't solve the cube at all and just have to DNF... sorry Ton but we are talking about methods which solve any scramble in as few moves on average as possible.

 

[JLarsen]

Well I read that ZB method has the potential of 40 moves on average. So it can be optimized even more

That's potential, not a realistic average. I'm pretty sure the shortest Petrus or Fridrich solution possible to any scramble could easily be near that number.