I've noticed a kind of "LW content inflation" over the years where what was once appropriate for Main becomes appropriate for Discussion and what was once appropriate for Discussion becomes appropriate for Open Thread. I don't know if this is a good thing or not. It seems like if you are asking a question that has an unambiguous answer then you should clearly post in Open Thread because it's fairly wasteful for additional people to see your question after it's already been answered; beyond that I'm not sure.