Colorado State Patrol does it too. As if a full size Whelen Liberty II Duo wasn't bright enough, they added front and rear inner edges. You know, because the second brightest lightbar ever made just isn't good enough.
If you don't synch it, it can be a mess but, if you do, it's impressive.
Our lightbar equipped Chargers are running an MPower lightbar and have a legacy traffic advisor on the rear deck. I'm steady burning the corner modules of the Mpower and then the entire lightbar and traffic advisor flash as one unit. The parking lots are also programmed to flash at the same time.
IIRC, it flashes at 75 fpm. This creates a massive foot print with a noticeable "pop" that really shows the location of the vehicle.
For the curious, our installer disconnected the legacy flasher and ran each of the eight light heads in the traffic advisor to the Blueprint system. I also use this to add a turn signal function during daylight hours.