Indeed there is a method and that very method is what bit them the hardest. Al qaeda had a time line, roughly about every 18 months. Al qaeda also had a pattern of escalating the scope of their attacks....bigger and bigger. That is what has bitten them. They cannot top 911, especially now that the USA is FINALLY fighting BACK.
Lets just say for the sake of conversations sake, that a train wreck here, a plastic plant explosion there, or a refinery fire over there actually are Al qaeda attacks. They are dismissed as accidents and they get no credit, thus a complete and utter failure of an attack. ( 11 Set the bar to high and it backfired on them in so many ways, including blowing their method right out of the water.
They have 18-month windows AND the use the configuration of that large star above a crescent moon, depicted on their flag, like it was last night.