If the amount of drugs can't be flushed in a short period of time, there's no need for a no-knock raid, right? And if it is small enough to flush, is it worth it to make the bust considering the risks involved in these raids?
Pretty much. You're not going to get a kilo of coke or a more than a handful of crack or meth down the toilet in a few minutes, so what's the justification for these no knock raids again?
If there are known to be heavy weapons and the will to use it, go ahead, raid. Otherwise, knock, give them 60-90 seconds(or whatever is the right number) and take out the door. That should be enough to save us regular, law abiding folks from this kind of insanity.