Invented flies?

How much of your tying time do you spend inventing flies, modifying flies
you invented vs. trying to make nice replicas of known patterns?

I like tying the standards, mostly because I feel like it removes one
variable from the game (like; will this actually catch fish?), but on the
other hand, its much more fun to just try things on my own. For example, the
other day I was making some Baetis Nymphs, and didn't have the right stuff
for the backs, so I used some brown chenille and trimmed it down with my
scissors. Eventually, I was doing all sorts of creative things, and SWMBO
looked over my shoulder and commented that they didn't look at all like the
pictures in the book...

--riverman