Are the patterns in the Effective Fly Box the only patterns you will ever need? No way.

I primarily fish for state sponsored trout. They will fall for everything in the Effective Fly Box, but they’ll * especially * fall for a sucker spawn fly tied in light or white using Nano Eggstacy yarn and fluorescent orange thread. I’m not going to be so dogmatic that I don’t catch that stocker bastard. I’m going to tie and fill boxes with egg flies.

The only fish less discerning than a stocked fish is a brook trout. Literally, eat anything. But on the streams (or more likely a specific stream) by you maybe more discerning fish only fall for a stonefly in size 12 with white legs and an orange body. You better tie those too.

The point is to catch fish with flies you tie. To do that tie the flies that the fish want to eat. But also tie the flies in the EFB, the fish probably want them as well.