Years ago friends would often poke fun at the flies I would use. Some were also customers who would grumble that I never tied them these flies whenever they were working well. They almost never ordered them though! It can be hard to get folk to pay for flies that are little more than thread on a hook. Which is fine, regardless of skill level anyone - even Paul ;) - can tie the kind of flies I'm talking about. Having said that, last time I was back in Scotland there were a lot of people talking about the a buzzer they were calling "the black death" because some competition team had done well on them. My mate showed me it.. The buzzer I've been using since about 1993; thread and a couple of turns of peacock herl. I saw it as a 10 year old in the now defunct Stillwater Trout Angler magazine. The next big thing! You've almost got to admire the brazen self promotion of the kind person who "invents" and publicises a pattern like that.
Buzzers or chironomids, are great illustrations of this. A look online will show you any number of patterns, some of them that go to great lengths to "imitate" various features. They'll all catch of course, I think that within reason it's almost impossible to tie a buzzer that won't. The question is, do all these elaborate patterns work better than a simple thread and rib fly? I doubt it.
There will obviously be days when fancier stuff will out perform the basic stuff, but over a year I doubt there'd be much difference. I'd be more confident in the simpler patterns. I know some people will agree with me, but if the people I tie for and those I see on the banks are indicative, most don't. Of the 3 in the picture, my preference runs bottom to top most of the time, but the most saleable is the black and red job.
Of course, it's fun to play with patterns and we can all use what we like but I would agree with Andy. The simplicity can be refreshing.