Very true. The flicker is not a sure thing. It matches the hatch size and color. And its action is a bit different. Trolling a bait is a different presentation from casting. It can be more productive at times and when you add in something different on top of a different presentation, you will have better luck.
Once the fish get used to seeing these, it won't be different anymore. There are so many fish in that lake, I don't think they'll get "used to seeing it" per say.
I'm new to trolling so I'm going with what I have confidence in as you said.