Ask low-commonality yes/no questions often enough to get them over the 30 threshold, while not tiring the user with too many experiences that they haven't had.
Perhaps ask >.5+ commonality questions 75% of the time, and <.5 commonality questions 25% of the time; or something similar.
When deciding which yes/no question to ask next, sample randomly from each bucket (i.e. a random selection from among all the <.5 questions, then a random selection from among all the >.5 questions).
Make sure not to ask the user a yes/no question they've already answered.
Ask low-commonality yes/no questions often enough to get them over the 30 threshold, while not tiring the user with too many experiences that they haven't had.
Perhaps ask >.5+ commonality questions 75% of the time, and <.5 commonality questions 25% of the time; or something similar.
When deciding which yes/no question to ask next, sample randomly from each bucket (i.e. a random selection from among all the <.5 questions, then a random selection from among all the >.5 questions).
Make sure not to ask the user a yes/no question they've already answered.