What I'm saying and you're ignoring is that by nature this can never be functional and safe (I used your words) because it's the unexpected death of a city (NO).
Death is messy... and to get all those people without mess.. sorry, it can't happen. It takes too long to mobilize because it just takes time. You can't say, in three hours, this must be done... Looks good on paper, maybe able to do it drills, but not in reality...
So, it does look messy. It does look like it is chaotic. Because it is.
So plans were devised that were not functional and safe?