I look at the off-season as a chance to practice techniques that make the flies better. For example, setting biot wings/tails on a prince nymph without a ton of thread.
As for patterns.. I live in Ontario, and have fly fished for trout here maybe 25+ years. When fishing in SW Alberta, I've found that allot of the smaller, low-riding emerger-type flies really perform well. In fact, I waited out a guy one night who was fishing for rising cutthroat with a massive foam thing. He was in a run I wanted to try before heading home, and I could see fish taking what looked like PMD emergers. No takers for him, so he reeled in and left. I found a CDC-winged, biot-body PMD in my fly box and using my nippers...cut the wing down about 2/3. First cast, a hefy cutty...and until dark, I spent more time landing fish than hooking the next one.
I'm a huge proponent of emergers, and looking for the signs of fish taking them. As such, flies like sparkle pupas are deadly and versatile. Even pond-fishing for stocked trout, a SP is one fly fish just can't seem to resist. lol Even if they don't take it dead-drift, impart a little action and/or swing at the end and hold on! Not the domain of 5X/6X tippet~the hits can be hard.
I tie another fly that works well as an attractor, an over-sized Griffith's Gnat with a copper bead head. Tied on a dry fly hook in size #16 with a few wraps of fine lead wire behind the bead to secure it.