Perhaps I misunderstand, buy surely you cannot compare the earthquake in Haiti and the Katrina flooding in the context of planning time. They were watching that storm for days before it hit,
I wasn't comparing the catastrophes that happened, I was comparing the response of each one. When people are starving, in need of medical care, heartbroken, etc... getting aid ASAP has to be immediate to keep the situation from turning violent. That's what happened after Katrina, and that's what's starting to happen in Haiti. People are afraid for their very lives and will react to that.