Depends on the box, but sometimes I see too many flies…or at least flies I don’t normally use. This is because in most situations (outside of a specific hatch or the fish keying in on something in particular), I tend to fish a handful of flies that I have confidence in from past experience…Wulffs, Adams Parachutes, EHC’s, Buggers, Scuds, PT’s, Ants. In many of these situations, I suspect other flies in my box will likely work just as well (or just as poorly depending on the day), but I don’t fish them simply because I haven’t done well on them before…not to say I couldn’t do well on them, I just stick with what works or at least has worked previously for me. Probably to a fault actually…I need to experiment more.
My Brookie, Limestone/Hatch Matcher, and WW boxes are pretty well pared down to stuff I use and actually regularly encounter, but I have one “General Trout Box” we’ll call it that has a little bit of everything…50% of which I’ve probably never used. I often feel the desire to trim this down to what I actually fish with, but I take this box when I don’t know what to expect on a stream and want to have a little bit of everything.
I’m pretty happy with my four fly box system at this point as my ultimate goal was to only have to carry one box at a time for a given outing. Each box contains a few of the above mentioned flies I fish most often, along with the other common things I encounter or need for that stream type. Most of the time it works pretty good.