Back in October there were a couple of discussions in this regard...
I put together a hatch chart (primarily for "The Basin") and go from that. During the off season I tie up flies that relate to those hatches. I made a fly case similar to the ones you see in fly shops, though not nearly as large, to hold my "inventory". When it's filled, I've tied enough....
My "basic" fly box (Okuma #155-10WHS) contains my standard dries (Adams, Elk Hair Caddis, Royal Coachmans, PMDs, and BWOs all in various sizes). On the clip side is where I carry my "standard" wets which consist of around 7 patterns all in various sizes. My nymph box (the smallest Wheatly clip) contains all my nymph patterns (5) in a wide range of sizes. My streamer box contains about 5 different patterns again in different sizes. These always remain the same. When the "super" hatches are going on I'll carry those flies in a small box (12 compartment) since some of these hatches do tend to overlap, plus the excess "standard" dries, namely Red Quills and Borcher Specials.
In my boxes, the flies are organized by pattern and size. My case is organized by type, pattern (in alphabetical order), and size...
My nymph box remains in the top right pocket of my vest, whilst the rest go in my duffle. For most of the season, I'm fishing out of my "regular" boxes and these are replenished out of the case as the season progresses. I try to keep 4 of each size fly in my boxes at any given time.
When streamside, my "basic" dry/wet box goes in the left chest pocket, steamer box in the right zipper pocket, nymph box, as mentioned, in the top right pocket, leaving the right chest pocket for the "hatch" box.
I don't tie as many patterns as it might appear; a total of 16 different dry patterns including terristials and what I call "specialty" patterns such as the Salmon Fly, Green Drake, Mighigan Mayfly, and Fall Caddis.
So, I would say that I do follow Hughes suggestion and have been for a very long time. The way I make it work is by concentrating on my presentation first, size of fly second, and having supreme confidence in both...FWIW.