[hintymad]

Thanks. I rarely saw this usage before, hence the question

[xaoz]

It's more common in less personal, more formal contexts. Another place you might see this in addition to hiring notes is police reports. It's fine English in any context though, just convention driven.

[nhaines]

It's been standard conversational English since the 1300s.

[hintymad]

Thanks. Somehow when I was learning English, the instruction was to use she/her to refer to an unknown third person, so did I when writing essays in a college here. That's why it felt strange when I saw they/their for 3rd person.

[eadmund]

No, it was not standard conversational English to use the third person plural to refer to a known individual man or woman. It has been used to refer to a non-specific person.

[ragall]

Far from "standard", more like occasionally used.