We fly fish warmwater(bass,crappie ,catfish,carp) a lot here in Ok. Usually we are not targeting a specific fish so most of the time we fish a two inch crayfish(size 4 4xlonghook) or a variation of a leadeye bunny leech on the same hook. if we go much bigger we lose the opportunity for crappie or carp. If We fish a popper on top we leave out crappie and catfish. We still fish on top when conditions are just right
We do fish satlwater size flies in the early spring and late fall when the majority of the surviving young fish of the year are bigger.
In june and july the ponds have a high percentage of small young of the year, and most of the bigger predators are keyed in. During this time of year we genrally fish with small marabou trailers behind are main fly and the trailors catch the majority of the fish.
Just my personal experience