Having been in this game a long time, i've met most creators more than once in a variety of venues.
Many Many of them are different from experience to experience.
Sometimes sketches are free, the next time they cost money.
Sometimes they want to engage you in conversation,
sometimes you feel like you're 'bothering' them.
A single experience often does NOT tell the story.
I just find it bizarre when the rules of getting a sketch or autograph changes dramatically depending on venue.
I also find it off-putting when a creator is at his table at a convention, but will only sign books 'the last hour of the convention.' -- That happened 2 or 3 times at HeroesCon this year. Then what are you doing at your table for 6-8 hours if you aren't meeting fans?