Another school in Michigan does intense drills/training with teachers for such situations. Some churches in the same area train for active shooters, too. IMO, not drilled enough.
I also practice moving through my house, clearing rooms silently in the dark - yes with a loaded firearm, with and without the dog. Granted, I only do that when I'm alone, I don't want to freak out my wife. ;-)
I know I know, some people reading this probably think I'm a little off, or I need a hobby. ;-) I have several hobbies, this kind of thing is just one of them.