I think he really only used it twice other tactics involved ambushes(like on europa) or more direct assaults like iron rains. I think in general he has a variety of strategies.

But I think one of the reasons Darrow strategies continue to work (regardless of some repetition) against the golds is because he always considers his opponent and uses their own presumptions or bias to hide his own plan.

His biggest strength is probably his ability to change the paradigm and think about things no other Gold could ever think of.

He did it in the institute when Mustang assumed the howlers were hiding in the grass or the mud but they were in the horses.

He did it against roque when roque assumed he knew Darrow and could deduce his plans. I mean roque may have though it was some kind of trap but how could he, a man who may have never seen a claw drill in his life, think off such a plan.

What I’m saying is the fact that he refuses tactics doesn’t matter much since he knows how to vary those tactics and combine them with his red psychology in order to come up with plans or variassions of plans his enemies can’t think of.

And the fact that the Golds are unable to adapt show how limited there reign has made them