My boys and I all tie flys but in truth we mostly do it during the winter.
It gives us something to do, just sit around the kitchen table, tie flies and talk about the fishing that will come in the spring, and it builds up our fly inventory.
Occassionally we will ge out and fish in the winter, but I like the dry fly fishing that comes in the summer more

I make a pretty decent nymph, but my favorite is the elk hair caddis dry fly. It works very well here in Utah.