Why distinguish 7 days and 1 week

Hello,

On the "New Faces" list, you can read

"7 days ago" and also "1 week ago"

which can look strangely different for the reader.

Wouldn't it better to use the unit "day" only up 6 days?

And then use the unit "week" from 7 days and above? (So 7 days would directly by displayed as 1 week).

I guess (but I did not check it) that the same smart unit switch can be useful for 24 hours and 1 day, and so on...