Learn English – Should you hyphenate ‘one hour session’

When I think of someone writing about office hours, or an hour at the office, I think of the words “office hours”, because in this case they are not being used as separate words put together (office + hours), but as one phrase that means a time spent at the office. I think your friend is thinking of the words as separate, their meanings individually. But put together and the plural “hours” doesn’t necessarily mean it has to be used for multiple hours.

For example, do you mean something like this?:

During my office hours, I spent an entire 45 minutes trying to print a report just to find out that my computer had somehow disconnected itself from the office network.

First, hyphens must never be used interchangeably with dashes (see the Dashes section link given below), which are noticeably longer. Second, there should not be spaces around hyphens.

Incorrect: 300—325 people Incorrect: 300 - 325 people Correct: 300-325 people

and in your case :

Proudly Sydney-Based is correct and no more anxiety about it,must used as headline.

reference:https://www.grammarbook.com/punctuation/hyphens.asp