One of the most severe difficulties associated with autism is the difficulty imagining what might happen in a situation. You could describe this as social imagination or just simply lacking instinct.
Most neurotypical people will go into any situation and be able to cope with it on the spot. The situation can be anything, for example going on the train, going to a cafe, meeting friends, going to the GP or going to a conference. In most instances they don't have to do much 'preparation' beforehand, or least not overly conscious or right-to-the-very-last-detail preparation.
Autistic people, on the other hand, have a tendency to either overprepare or underprepare.