The theory behind right-left-center I believe was related to they wouldn't change position in their formation, so they wouldn't warp as much.
I don't find much of an issue with that, and if I'm doing the stupid dead-six suicide charge with a heavy cannon plane, I like to shoot the left one and then switch to the lead. That way the right one moves across my sight behind the lead and hopefully I can spray them both down.
I've heard rumors shooting the lead messes with calibration, but have never confirmed it. Are we talking a slightly different airspeed when you switch to the drone, like by <5mph?
Wiley.