I've noticed that some submissions drop off the news feed like a rock, while other submissions of the same story posted just a few hours later can gather considerable discussion, with submission time being the only apparent variable. This leads me to speculate that there may be an optimal submission time or times throughout the day. I'd like to see analytics that look at the variation in the average number of comment…
It's been discussed several times on HN, for example here: http://news.ycombinator.com/item?id=4058492 and (original submission I think): https://news.ycombinator.com/item?id=3251877