So I'm pretty new to casting reels last year was my first full year of using them. I have a question when I'm fishing a crankbait or a jerkbait do you keep your drag in play obviously, not tightened down all the way or too loose. I get if I'm fishing a frog or flipping the drag is locked down. But how do you handle the other scenario?

Definitely back off drag for trebles.  I do it by feel but I'm sure someone will come on and tell you how they use a scale to precise amount of drag.

That would make more sense if I was using braid with a fast action rod but if had fluorocarbon or co-poly with a moderate rod would that make a difference.

The drag should be set to a level that will protect the line, rod and reel regardless of technique or tackle style. 

For those type of baits I usually consider first the hooks if I'm fishing treble hook baits. A lot of those jerkbaits and some crankbaits come stock with small light wire hooks and even using 8lb line you could bend them if you lock your drag. Then from there if the hooks will be fine I consider the line breaking strength.