[throwaway1777]

So you’re saying there should be a difference between 1 day and 2 weeks, but the google story said otherwise, basically no one could tell.

[AlbertCory]

More accurately, not enough people could tell to be statistically significant. This is all explained on the video.

People who say "use 4 weeks" are right. It's just hard to organize a whole lot of these things. We're lucky we could do it once.