You are dead on about applying this rule to lake fishing and warm water but dead wrong about coldwater creek fishing. And the rule of thumb you are describing is 100% accurate for lakes. Devil is in the details and flowing coldwater creeks are totally different. These aren’t opinions.Do what you feels right. Anything above 76 I wouldn’t fish. Sorry you feel the need to defend yourself. You seem like an expert. We can fish anytime and I guarantee we would have a blast. And we would both teach each other something.