Most people, who train in martial arts, are not the primary example of a warrior with all of the psychological traits. The fact is you could be walking down the street thinking about your job, family, training and somebody comes up to you and says "Excuse me. My phone battery died. Can you tell me what time it is?" you say "Sure, it's..." BAM. You wouldn't even know what hit you. Not to mention other situations, after drinks, exhaustion after a hard training, day at the job etc. Even in the old days warriors where killed in ambushes.
Sure, but isn't the whole idea to avoid such lapses of attention?
Certain techniques like Ikkyo are always available. What i was asking is how would he technically train against a sucker punch not what specific technique he could use. The fact is anybody can be punched like that, the only thing you can do is work on your movement, body positioning, so you don't stand right in front of somebody on the street, Maai or distance between you and the person you are talking to and most importantly to get your hands up as fast as possible.
If you're managing distance and body positioning, then by definition you're not "careless" and "unaware."
And ikkyo absolutely is not going to be available to defend against a true sucker punch that you don't see coming. You throw your hands up in a "flinch" reaction and the attack drives right through them.