Y'all got me really confused with this....
I've watched a number of videos and read lots of different opinions on this. I look at my Kanger OCCs, and they are spaced. I build my PT2 heads as tensioned microcoils. I'd read a number of times throughout ECF that spaced coils "spread out" the heating so that "more surface area" is available to vaporize the juice.
Agreed that you shouldn't choke the wick. I typically wick with cotton, and looser is better (for me) in that as the cotton expands with juice, the flow is less likely to get cut off. When I first started playing with my kayfuns, I'd already been building my PT2 heads on a 1/16" drill bit (30g.) That works marvelously well in those heads. However, for me to avoid the burnt hits on my kayfuns, I had to start building larger diameter coils (using 1/8" bit - sometimes 30g, sometimes 28g), and so many of my dry hit issues seemed to be resolved.
I've tried rebuilding some of my OCCs, but using a spaced wrap on a 1/8" bit. Jury's still out on this method, and smallest gauge wire I currently have is 28. The pre-installed coil that came with my STM RBA head is "loosely spaced" and now that I have my wicking right, it's hitting like a champ. I don't pre-torch my wire - I'll fire it after I have a measured build, just to check for hot-spots and even glow. Then I wick it up and load my tank....
For me, to achieve more surface area, I'm starting to twist my wire. I'm running a twisted 4-strand 30g coil on one of my RDAs, and this thing is a monster. The wraps are touching, but not tightly compressed.
All I know is what I'm doing seems to be working (most of the time).... I have only myself to blame if I can't get it wicked correctly.