I’ve seen albies/bones turn off a fly if they’ve zeroed in on it and the retrieve suddenly slows for any reason. I believe the strip doesn’t have to be of warp-speed cadence, but that the fly should appear to be up-shifting gears a bit as it “senses” it’s being singled out of the pack. A dead-drifting fly might work, but personally I prefer a more active role in giving the fly a life-like appearance.