I have 4 powerheads running different wavemaker options in my 75. 2 Koralias, and 2 Maxi Jet 1200's.
I'm of the opinion that random is better for corals. Although my setup may be to the extreme! I have an old wavemaker box that Shane Heil made me 10 years ago that has adjustable potentiometers to change the cycle rate and on/off time that I run through my controller with an "oscillate" (random) pattern during the day only. My controller sends power to the wavemaker box randomly which then cycles the powerheads based on the settings I've chosen there. I twist the knobs periodically to make it even more random, but I usually don't go shorter than 2 seconds on or longer than 2 minutes off. These 2 power heads are in the back bottom corners pointing along the back bottom of the tank towards each other.
I also have 2 MJ1200 powerheads running on a Red Sea Wavemaster controller. They are pointing up and forward from the back bottom corners and also run on a random "reef" setting. They seem to cycle on and off fairly consistently, so I wouldn't call it truly random, but they are also in the range from a few seconds to maybe a few minutes. It also runs a calmer program at night.
On top of that, I run a Sea Swirl oscillating return, which sweeps back and forth 90 degrees every 60 seconds, interacting with the flows created by the powerheads.
Like I said, MAYBE

a bit extreme, but it's working great for me, I have excellent polyp extension but one day would love to get a couple of Vortech MP10 or MP40's and call that good.