I think "longer" referred to the length of time the question goes unanswered - not the number of characters it took to pose the question. While you can't quant

I think "longer" referred to the length of time the question goes unanswered - not the number of characters it took to pose the question. While you can't quantifiably measure difficulty, it's fair to say that more difficult questions will remain unanswered longer. Easy questions get pounced on. The difficult ones take time.