If you have done extensive research on a topic, or have years of experience on a topic, and you focus for even 5 minutes on a quality answer, that will already generate a long answer. On a website with as many users as Reddit, there’s bound to be a user with those qualifications to make a comment on a topic that relates to their interest. That topic will likely get upvoted to the top (generally speaking).
Not so much on the time, but more on the how:<p><a href="https://old.reddit.com/r/AskHistorians/comments/2s21av/meta_how_a_great_answer_on_raskhistorians_gets/" rel="nofollow">https://old.reddit.com/r/AskHistorians/comments/2s21av/meta_...</a>