The last Cyano outbreak I had was in a high flow tank growing right where the powerhead was blasting. As I mentioned earlier though even a high flow tank can have deadspots and if they are not dealt with can lead to cyano or other algae's + nutrient increase.I am not a big believer in NP ratios, etc - since I've seen Cyano in nearly every condition - and even after many years, I can't predict where it might grow. When it comes to water chemistry, local levels may be more important than levels in the tank. I have noticed that no matter what the chemistries, cyano does not do well in tanks with high flow.
Nutrient balance may not be a big factor with Cyano, but is clearly a very important aspect of tank chemistry and health. I still think it is a factor for Cyano and other algaes as well.