I generally agree with this. But based on what I read/watched on Wealthfront, they don’t encourage or even expect you to realize capital gains regularly. What they do suggest is being opportunistic about short-term losses. So if buy 10 ETFs in 2016 and one of them is in red by November, sell it and replace with a similar-risk asset to maintain the same overall risk. I think they suggest selling for short-term losses multiple times a year, and it’s likely automated.