Jeremy,
I would keep a few handy. I think when Caddis are hatching, or around the water, they may work. The stripping retrieve, as I mentioned, has worked in the past anyway....for me.
I used to fish Bennett Spring in Missouri, and a lady I know who has/had a shop there swears by them!!
When I saw her fishing, I would ask what she was using. Almost always was a crackleback in late afternoon/early evening.