you can train a pigeon to play ping pong...in other words learning to tie different flies is a matter of practice. I tie all my own flies and have done so since I was 10 ( 30 years ago now!). I can tie virtually any fly I want including full dress if necessary. It is not necessary.
Full dress flies take longer and are more expensive with all the fancy feathers. I know they do not fish any better. They look pretty and as the old saying goes" the fly must catch the fancy of the fisherman first". I hate to lose these beauties I spent an hour making so I don't fish them much. I catch most of my fish either on my own patterns or variations of other patterns that I "tag" as my own ( change part of the pattern to make it semi-original). These flies are hair wing type patterns or tube flies as a rule.
Confidence in the fly is as important as anything else. Fly size, shape, color and presentation are in my mind what works. Most important above all is presentation.
In buying a house it is location, location, location. In atlantic salmon fishing it is presentation, presentation, presentation.