It’s simply an algorithm. How many times you refresh a page, how many times you log on. How long you are on a page.
Granted, for those of us with toddlers and other distractions it may be several hours, when in reality, we just spent minutes because we left the page up while we changed a diaper, or swept the floor or a million other distractions. I freelance write and I come to CAF between articles to help my brain recharge and refocus. The page is almost always up…so I’m sure that skews things.