There may, perhaps, be cases where a no-knock warrant is appropriate. The actual number of such entries is far larger than the likely number of appropriate uses of that method.
Check out the killing of a Houston couple by the police in a no-knock raid. Raid was based on false information actually provided by the police who led the raid.
There may, perhaps, be cases where a no-knock warrant is appropriate.”
Bonnie and Clyde, Dillinger etc but probably not Capone. That sort of thing.