FWIW, the only way to build a coil wrong....  Is when the resulting coil doesn't work. 
I prefer a loose twist of say a 2mm-3mm pitch over parallel or a tight twist.  I don't do fancy, but I do prefer the flavor of twisted wire over single strand.  BUT, single strand gives me a little more time between rewicking sessions.  So, for me single strand vs twisted wire comes down to...  When do I want to service the atty next.  In my drippers I tend to do twisted wire.  On my Kayfuns and tube mech I tend to do single strand.  Reason it's easier to service the drippers than it is the tanks.