Ok. here is what I use (for now)
box 1...dries...trout only.
box 2... nymphs, eggs, worm patterns...trout, carp, steelies,smallies
box 3... dark streamers... trout, steelies, smallies, walleye, sauger,pike
box 4... light streamers... white bass, hybrid bass,gar
This is a funny post for me because how I arrange my boxes (yeah, that does sound weird) changes about once a year. Currently I have a small box hanging from my lanyard with the flies I think I will need that day, and a larger box in my pack with flies that I might need that day, or that I might need if I go to Russia that day. Then I have about four boxes at home with residual flies I tied arranged roughly in the following way:
Experimental or don't fit in the other categories.
What a coinkydink: I just rearranged all my boxes a couple of weeks ago. The dry box was a mess and the hackles on the larger ones were getting squashed. Also there were a lot of bugs in there from long ago that were really UGLY.
So, now I have drys, nymphs, stones, streamers, one box each large and small. Come summer, I'll find a deeper box for those big buggy drys.
And since I'll end up with flies from the turkey swap AND the nymph swap, I'll probably have to find a bigger box for those.
Part of the problem is that I'm not fishing enough. I'm a guy who thinks that there's a fish under every log. I'm a sucker for a log jam or a sweeper. I gotta fish 'em to a froth, till the logs got more feathers on it than a duck. I should be out losing flies like crazy. Then I would have plenty of room in the boxes.
I have a mayfly box (its life cycles of any that I will encounter) , a caddis box, a still water/trrestrial/wet fly box (it is a huge box), a streamer box , a smelt fly box , a salmon fly box (this is also huge and bulging might need another).
I carry the mayfly, caddis, and still water boxes, always
If I remember Ill take the smelt fly box when Im going to need it