I think people get too caught up with the ought's and denier meaning the same thing when they don't. Some people will just say well, that Gordon Griffith's 14/0 is the same denier as that 55 denier GSP so it's the same diameter etc... when if you look at it, the 14/0 is in my opinion thinner thread but if you cut the same length of it and GSP it weighs the same but that just means its a heavier material.

Gordon Griffith's is my go to thread for almost all my flies, sometimes even my big striper flies when I'm too lazy to change it except for spinning/stacking hair. I tied a size 30 using spiderweb..... some guys will split spider web and use that for tying really small stuff or intricate work.... how they do that is beyond me. The only thing about using small thread is it can create durability issues. Not so much that it's fragile, but more so it's prone to bite or cut into materials creating a weakness at the tie in point especially with hair wings etc..