In general, I'd say that, for example in wills and parish records, if someone was described as "of Watford", for example, the reference was not casually made. But people could move from one parish to another in the course of a lifetime. Wills often show people holding land in more than one parish. As a result of the Poor Laws some parishes restricted movement into them of people who might become a burden on the parish. Others were more willing to accept newcomers.
So, briefly, when parish records, wills, and other sources show a person as of a particular place, this has meaning, but it's not carved in stone.