There's the rub. There are a number of factors that would come in to play. I guess I'd need a checklist to see if the needle moved far enough over to justify the no-knock. Violent felony? Armed? Criminal history? History of resistance? Who else is, or might be, inside? Victims? Kids? Is it an apartment (shoot-throughs are a concern), a single dwelling, or a trailer in the middle of 10 acres? Is there another way, or is this the only viable option? Can we surround and do a "call-out"? Use OC / gas? Will it likely be a gunfight regardless? What do I gain, or risk losing, by using this tactic? Are we talking about 2 kilos of coke, or 2 armed gangsters? Coke never shoots at you, in my experience. Meth lab? Do I want to risk a spark or flame?
Not saying I'd get it right every time, but if we could eliminate 50% of our mistakes, would that not be a good thing? Being a Chief, or Sheriff, hopefully one would have years of experience from the street-level up, and so could think about "all the ways this could go wrong", and ask the right questions.
All that being said, I'm glad I don't have to make those decisions. And I'm not running for Sheriff, so...