I used to fish adult patterns (Elk Hair Caddis) most of the time, at least here in the East, primarily for visibility; it also served as an excellent general attractor. Out west, where I've hit some pretty heavy caddis hatches, I found emergers worked better and fished mostly Iris Caddis, X-Caddis/X2 Caddis, etc. Last year I started using CDC & Elk and found it was pretty effective throughout the hatch and that's become my go-to fly, as an attractor on the little local freestoner, and on the larger western streams when there's any caddis activity.

Regards,
Scott