Interesting conjecture, except you forget a few details.
First, "maximum chaos" would happen if they did set them all off at once. Second, if they set them all off at once, they don't have to worry about stepped-up policing efforts discovering any of their other weapons before they can set them off.
And, even apart from those two factors, there's the biggie: coordinated multiple/simultaneous attacks are AlQ's trademarked MO. It's what they do.
You offer what?¿ to support that opinion?