If I'm using chicken or turkey giblets for bait, I'll use a treble hook. It's just way easier to secure it. Or with lures. Though I've had some luck replacing trebles on plugs with a larger single hook. Otherwise, I use singles. I usually use worms, minnows, or small bluegill for bait, and the singles have worked best with them for me. Easier on the fish and the hands as well.
if im limblineing trotlineing or jugging for huge flatheads I use a big circle hook..now if its bass striper or whatever it will be treble hooks on a rapala jointed shad rap...
As far as an individual hook, almost always a single, but occasionally a treble. Often times though I will have two tied on at the same time. Of course if I'm using a lure I stick with whatever hook(s) it came with.