That sort of data can be extremely useful to pattern someone. Most people brush their teeth either in the morning, or before bedtime (or both ideally.) So just

That sort of data can be extremely useful to pattern someone. Most people brush their teeth either in the morning, or before bedtime (or both ideally.) So just knowing _when_ they're brushing their teeth you can determine their sleep pattern, and thus match that up somewhat to a timezone. On it's own this isn't incredibly useful, but combined with some other data it becomes a lot more useful to identify someone.