In a live show, when playing back on-the-fly (busking, winging it, or punting), I find using the grand master and DBO button very helpful. I will often ride the grand master fader up and down with the beat of the song or flash the DBO key accordingly. By doing so, I can flash or pulse the entire rig without having to create a special button to do so. However, I must be conscious of the fact that the grand master controls all intensities on the desk. So this means that any media servers, smoke machines, non-dims, etc., will also be turning on and off. In some cases, use of the grand master may not be desirable simply because it does control all fixtures in the desk…At some point in everyone's lighting career, they will find themselves sitting at a lighting console not able to figure out why there is no output from the desk. You will troubleshoot for minutes or hours trying to determine why nothing is coming up. Eventually you look across your desk and realize the grand master is at zero. Don't worry, this happens to everyone at least once!
-Brad Schiller, from Feeding the Machines, PLSN, Dec. 2010.
