Re: single haul
Good one Calftail ! You're right, there is little need for double hauling in most river fishing, and, in fact, it is generally counter productive to be a long ways from the fly in the first place. And as Ard says, lining fish is all too easy to do.
So that may be one reason why it's talked about so much. Guys don't normally learn the technique at an early age, then they hear about it when they decide to try salt water and don't know anyone to show them the technique except on youtube.
So it gets talked about a lot on the forum.