readywhenyouare, every situation is different and not all warrant an evacuation. The requirement to be able to evacuate a plane under 90 sec when warranted, does not mean that is procedure for every situation. You must assess possible threats inside and outside the aircraft and use your judgment and any information that you might get from crew members including flight deck and cabin, and pax. Sometimes it could be safer to remain on the aircraft. Communication and assessment of elements and surrounding environment (if communication is not possible) is critical to decide if you will evacuate and which exits you will use. However, when "in doubt, get out'.